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263 Cards in this Set
- Front
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- 3rd side (hint)
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RNA Molecules that exhibit catalytic activity are called:
A) mRNAs B) ribonucleases C) ribosomes D) ribozymes E) ribonucleotides |
D
Only enzyme that would have catalytic activity. Therefore ribozyme would be the choose. |
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The conversion of pyruvate to oxaloacetate is likely to require which of the following coenzymes?
A) Biotin B) vitamin B12 C) thiamine pyrophosphate D) pyridoxal phosphate E) Flavin Adenine dinucleotide |
A
Biotin transfer carbon dioxide. It is used for cell growth, the production of fatty acid, metabolism of fats and amino acids. It is also used in the Kreb's cycle. Vitamin B12 is not the answer because the function of Vitamin B12 is to transfer methyl group between two molecules or rearrangement of hydrogen that is directly transfer between adjacent molecules. Thiamine Pyrophosphate (TPP) cleaves bonds adjacent to a carbonyl group and transfer aldehyde group is transferred from one carbon atom to another. Pyridoxal phosphate (PLP) acts as a coenzyme in all transamination. Flavin Adenine dinucleotide (FAD) is used for protons transfer for the electron transport chain when FAD is turned into a high energy carrier FADH2. |
Flavin Adenine Dinucleotide = FAD
Thiamine pyrophosphate = TPP Pyridoxal phosphate = PLP |
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Which of the following hormones initiates biological actions by crossing the plasma membrane and then binding to a receptor?
A) Glucagon B) Estradiol C) Insulin D) Norepinephrine E) Adrenocorticotropic hormone |
B
The answer is Estradiol because it is a form of Estrogen which is like steroid and it is derived from cholesterol. Glucagon is a hormone signals the liver to produce and release more glucose when blood glucose decreses. Glucagon binds to a glucagon receptor which signals a release of glycogen, a storage form of glucose. Insulin can control the glucose intake and with the extra glucose intake, insulin can stimulate a reaction to form glycogen to store the glucose. It can also increase the DNA replication and protein synthesis via the control intake of amino acid. Norepinephrine is a stress hormone. It underlies fight or flight response, increase heart rate, triggering the release of glucose from energy stores, and increasing the skeletal muscle. |
Steriod initiates biological actions by crossing plasma membrane. Which of the chooses is a steriod?
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Which of the following takes palce during oxidative phosphorylation in mitochondria?
A) Protons are pumped from matrix to the intermembrane space. B) Protons are pumped from the intermembrane space to the matrix. C) Electrons are pumped from the matrix to the intermembrane space. D) Electrons are pumped from the intermembrane space to the matrix. E) NADH is pumped from the matrix to the intermembrane space. |
A
All the complexes are located in the inner membrane space. The electron transport chain is to transfer electron through a chain of complexes by pumping protons out at the same time. Protons are obtained by FADH2 and NADH. Protons are being pumped from Matrix into the cytosol area also known as intermediate space. The electrons from the oxidation of NADH and FADH2 never leave the inner membrane space. |
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An enzyme that catalyzes the reaction A<=>B changes the
A) heat of reaction B) equilibrium constant C) equilibrium concentration of A D) entropy of the reaction E) rate of both the forward and reverse reactions |
E
Enzyme can only change the rate of both the forward and reverse reaction because the enzyme can speed up the reaction to produce product. If the product is enough then the product can act as a feedback inhibitor which can shut down the reaction from producing more products. |
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The major mechanism of turnover of molecular components of the plasma membrane occurs through
A) endocytosis of patches of membrane B) diffusion of individual molecules into the cytoplasm C) recovery of specific components by selective receptors D) explusion of integral molecules into the extracellular medium E) the concerted action of multifunctional enzyme complexes |
A
The Major mechanism of turnover of molecular components of plasma membrane occurs through endocytosis of patches of membrane because when cell undergo apoptosis the materials in the cell is degraded and it is taken up by neighboring cell by endocytosis such as phagocytosis or pinocytosis. The mechanism does not depend on diffusion of individual molecules into the cytoplasm because in the cytoplasm there are already certain amount of molecules and diffusing through the plasma membrane needs to be diffuse through channel gate which is opened and closed by the gradient. It does not depend on explusion of integral molecules because integral molecules stay in the plasma membrane and it doesn't not leave the plasma membrane. |
Think clearly. Individual molecules are referring to H+ or Na+ etc.
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Cells with abundant microvilli are characteristically found in
A) Exocrine glands B) the reticuloendothelial systme C) adipose tissue D) neuronal dentrites E) absorptive epithelia |
E
Cells with abundant microvilli are characteristically found in absorptive epithelia. First I thought of microvilli as the little hair thing that you find in the small intestine. Because it is used to absorb the molecules from food that is being digested. The answer can not be exocrine gland because it secrets product into duct. Exocrine gland includes sweat gland, mammary gland, salivary gland and many glands from the digestive system. Reticuloendothelial system is found in the immune system. Adipose tissue is a loose connective tissue or also known as fat. It is use for storage of energy in the form of fat. Dendrites are neurons that conduct electrical signal in the nerves. |
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Diacylglycerol activates which of the following enzymes?
A) Protein Kinase A B) Protein Kinase C C) MAP Kinase D) Tyrosine Kinase E) Phosphorylase b Kinase |
B
Diacylglycerol is used as a second messager to activate protein kinase C (PKC). Diacylglycerol is activated by Ca2+ after a signal activates a G protein. The process how the diacylglycerol is activated is by phosphorylating GDP to GTP after G protein was activated. This involve the αβγ subunit. Then Phospholipase C is activated by GTP which activated DAG. DAG releases IP3 that release Ca2+ from the ER. Ca2+ then activates PKC which binds to DAG that produces cellular response hormone. PKA is activated by epinephrine. When epinephrine is bound to the receptor, a signal is send to produce cAMP from ATP. The production of cAMP is then used to activate PKA. Activated PKA is used to activate phosphorylase b kinase. Then the activated phosphorylase b kinase is used to activate glycogen phosphorylase b which produce glycogen phosphorylase a. Phosphorylase a caused a rapid mobilization of glucose from glycogen. Glycogen is first cleaved to produce glucose 1-phosphate and then with multiple step produce glucose. The answer can not be MAP Kinase because MAP kinase is related to growth. It is a cascade reaction that relate to growth. MAP Kinase Kinase cleave to MAP kinase and it is cleave to MAP which activate growth. Phosphorylase b kinase look at above that refer to PKA. |
Diacylglycerol = DAG
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Cellular proteins destined for secretion are sorted and packaged in the
A) Lysosomes B) Endosomes C) endoplasmic reticulum D) trans Golgi network E) peroxisomes |
D
Trans Golgi Network is to modify, sort and package protein for secretion in exocytosis or use within the cell. Trans golgi network, think of post office. Sort the mail, package mail together that are going to the same place. Lysosme contains enzyme capable of digesting proteins, polysaccharides, nucleic acids and lipids. They break down the complex molecules then brought into the cell by endocytosis or phagocytosis. Lysosome is les active at the higher pH of the cytosol. Endosome is a small vesicle. Peroxisomes breakdown amino acid and fats by oxidative reaction. Hydrogen peroxide is degraded by catalase. |
secretion = the act or process of separating, elaborating, and releasing a substance that fulfills some function within the organism or undergoes excretion.
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Incubation of gram-negative bacteria with lysozyme in an isotonic medium causes rodshaped bacteria to assume a spherical shape. The cause of this phenomenon is
A) absorption of water B) destruction of cell wall C) destruction of the cytoskeleton D) damage to the plasma membrane E) change in gene expression |
B
Destruction of the cell wall |
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Virus-mediated transfer of cellular genetic material from one bacterial cell to another by means of virus particles is called
A) induction B) transfection C) transformation D) transposition E) transduction |
E
Tranduction transfer of bacterial DNA from one bacterium to another by virus. Induction has to do with inducer of a gene. It refers to initiation or cause of change. Transfection is an introduction of material into a eukaryotic cell. Transformation is DNA transfer from one cell to another by plasmid or yeast or bacteria. Transposition is that a sequnece of DNA can be move around to different position within the genome of a single cell. |
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Which of the folloiwing processes lead to formation of polytene chromosomes?
A) Nondisjunction of chromatids during meiosis B) Recombination between adjacent chromosome segments C) sister Chromatid exchange D) Inactivation of one chromosome of each homologous pair E) repeated replication without separation of chromatids |
E
Polytene chromosomes form when multiple rounds of replication produce chromatids that remain synapsed together in a haploid number of chromosomes. |
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True Statements about retrotransposons include which of the following?
I. They replicate through an RNA intermediate II. They utilize reverse transcriptase for replication III. They may contain introns. A) I only B) III only C) I and III only D) II and III only E) I, II and III |
E
Retrotransposons copy themselves to RNA and then, via reverse transcriptase, back to DNA. Retrotransposons, also known as class I transposable elements, consist of two sub-types, the long terminal repeat (LTR) and the non-LTR retrotransposons. |
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Which of the following is true about a cicular double-stranded DNA genome that is determined by chemical means to be 21 percent adenosine?
A) The genome is 10.5% guanosine B) The genome is 21% guanosine C) the genome is 29% guanosine D) the genome is 58% Guanosine E) the base percent composition of guanosine in the genome cannot be determined from the information given. |
C
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In the classical model of transcriptional control described by Jacob and Monod, a repressor protein binds to
A) an enhancer B) an AUG sequence C) an operator D) a ribosome-binding site E) a TATA box |
C
Repressor proteins are coded for by regulator genes. Repressor proteins then attach to a DNA segment known as the operator. By binding to the operator, the repressor protein prevents the RNA polymerase from creating messenger RNA. |
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In an intact cell, the free energy (ΔG') associated with an enzyme-catalyzed reaction is frequently different from the standard free energy change (ΔG°') of the same reaction because in the intact cell the
A) activation energy is different B) reaction is always near equilibrium C) enzyme may be regulated allosterically D) reactants are not at 1M concentrations E) reaction may be catalyzed by more than one enzyme |
D
Reactions are not at 1M concentrations |
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plants and some bacteria differ from animals in that plants and some bacteria can
A) form polymers from glucose B) use carbon dioxide to increase their biomass C) produce NADH via reductive reactions D) synthesize glutamate and aspartate E) use glucose by the glycolytic pathway |
B
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Which of the following can act as nucleophile in metabolic reactions?
I. Nitrogen of an amino group II. Oxygen of a hydroxyl group III. Carbon of a carbonyl group A) I Only B) II only C) III only D) I and II only E) I, II and III |
D
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In addition to proteins, major components of very low density lipoproteins (VLDL) circulating in the blood of a normally fed mammal include
A) Triacylglycerol, cholesterol, and phospholipid B) Triacylglycerol, squalene and phospholipid C) triacylglycerol, squalene, and sphingosine D) monoacylglycerol, cholesterol and phospholipid E) monoacylglycerol, squalene and sphingosine |
A
VLDL transports endogenous triglycerides, phospholipids, cholesterol and cholesteryl esters. It functions as the body's internal transport mechanism for lipids. It is assembled in the liver from cholesterol and apolipoproteins. |
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Elevation of intracellular inositol trisphosphate (IP3) results in a release of Ca2+ from which of the following organelles?
A) Peroxisome B) LYsosome C) Mitochondrion D) Nucleus E) Smooth Endoplasmic reticulum |
E
Smooth endoplamic reticulum release Ca |
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Which of the following is the last to occur after the binding of a sea urchin sperm to an egg?
A) Increase in cytosolic pH B) Increase in calcium concentration C) Activation of protein synthesis D) Initiation of mRNA synthesis E) Exocytosis of cortical granules |
E
In sea urchins, the block to polyspermy comes from two mechanisms: the fast block and the slow block. The fast block is an electrical block to polyspermy. The resting potential of an egg is -70mV. After contact with sperm, an influx of sodium ions from the sea water increases the potential up to +20mV. The slow block is through a biochemical mechanism triggered by a wave of calcium increase. The rise of calcium is both necessary and sufficient to trigger the slow block. In the cortical reaction, cortical granules directly beneath the plasma membrane are released into the space between the plasma membrane and the vitelline membrane (the perivitelline space). An increase in calcium triggers this release. The contents of the granules contain proteases, mucopolysaccharides, hyalin, and peroxidases. The proteases cleave the bridges connecting the plasma membrane and the vitelline membrane and cleave the binding to release the sperm. |
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All of the following are true about heterotrimeric G proteins EXCEPT:
A) They bind either GDP or GTP B) They have GTPase activity C) They act as binary (on-off) switches D) They help amplify a hormone's signal E) They phosphorylate proteins |
E
They phosphorylate proteins |
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The completion of the S phase of the cell cycle of a mammalian cell is marked by all of the following EXCEPT:
A) Histone content per cell is double that of cells in G1 B) In replicated DNA, newly incorporated bases are paired with parental bases. C) Each replicated chromosome has four telomeres D) sister chromatids disjoin from one another E) The nucleus contains the equivalent amount of DNA of a tetraploid cell in G1 |
D
The S phase, short for synthesis phase, is a period in the cell cycle during interphase, between G1 phase and the G2 phase. Following G1, the cell enters the S stage, when DNA synthesis or replication occurs. At the beginning of the S stage, each chromosome is composed of one coiled DNA double helix molecule, which is called a chromatid. At the end of this stage, each chromosome has two identical DNA double helix molecules, and therefore is composed of two sister chromatids. During S phase, the centrosome is also duplicated. These two events are unconnected, but require many of the same factors to progress. The end result is the existence of duplicated genetic material in the cell, which will eventually be divided into two. |
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In the lysosomal storage disease called I-cell disease, all of the hydrolases normally found in lysosomes are instead found in bloodstream. Which of the following is the most likely cause of this disease?
A) Lack of phosphorylation of lysosomal enzymes B) A nonfunctional proton pump in the lysosomal membrane C) A mutation in the clathrin gene D) inability of the endoplasmic reticulum to form lysosomal vesicles E) Absence of sialic acid on glycolipids in the Golgi complex |
A
Lack of phosphorylation of lysosomal enzymes Lysosomal enzymes are synthesized in the cytosol and the endoplasmic reticulum, where they receive a mannose-6-phosphate tag that targets them for the lysosome. Aberrant lysosomal targeting causes inclusion-cell disease, whereby enzymes do not properly reach the lysosome, resulting in accumulation of waste within these organelles. |
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All of the following contribute to promoter binding by RNA polymerase in E. coli EXCEPT the
A) rho factor B) -10 consensus sequence C) -35 consensus sequnece D) β' subunit of RNA polymerase E) β subunit of RNA polymerase |
A
Rho factor |
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"Zinc fingers" are important in cellular regulation because they are
A) at the catalytic site of many kinases B) a structural motif in many DNA- binding proteins C) characteristic of palindromic stretches of unique-sequence DNA D) restricted to the cytoplasmic domain of growth-factor receptors E) structures with high redox potential |
B
A structural motif in many DNA-binding proteins |
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In prokaryotes, environmental sensing frequently involves regulatory proteins (two-component systems) that sense and respond to changes in surroundings. These two-components systems may involve which of the following?
I. Protein phosphorylation II. transcriptional regulation III. Membrane proteins A) I only B) II only C) III only D) II and III only E) I, II and III |
E
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In the cross AaBb x AaBb, Mendel's principle of independent assortment predicts that the ratio of the four possible phenotypes of the offspring will be
A) 1:1:1:1 B) 3:2:2:1 C) 4:2:2:1 D) 9:3:3:1 E) 9:7:3:1 |
D
Independent assortment |
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Common lesions found in DNA after exposure to ultraviolent light are
A) pyrimidine dimers B) single strand breaks C) base deletions D) purine dimers E) transpositions |
A
pyrimidine dimers |
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The reaction shown above is conducted in a closed system containing gaseous CO2 and a buffered aqueous solution. If the reaction is allowed to reach equilibrium, the final concentration of bicarbonate ions in the aqueous phase would most likely be increased by
A) adding water while keeping the partial pressure of CO2 constant B) adding carbonic anhydrase C) increasing the pH of the buffered aqueous solution D) reducing the partial pressure of CO2 E) reducing the temperature of the reaction solution |
C
Increasing the pH of the buffered aqueous solution |
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Which of the following types of bonds or interactions are LEAST likely to be involved in stabilizing the three-dimensional folding of most proteins?
A) Hydrogen bonds B) Electrostatic bonds C) Hydrophobic interactions D) Disulfide bonds E) Ester Bonds |
E
Ester bonds |
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In animals, an enzyme unique to gluconeogenesis is
A) enolase B) phosphoglyceromutase C) glyceraldehyde 3-phosphate dehydrogenase D) aldolase E) fructose 1,6-bisphosphatase |
E
Fructose 1,6-bisphosphatase Enolase is an enzyme that participates in glycolysis. Phosphoglycerate mutase (PGM) is an enzyme that catalyzes step 8 of glycolysis. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH or G3PDH, although this is less accepted)catalyzes the sixth step of glycolysis, comprised of two reactions. Aldolase A is an enzyme which catalyses one of the aldol reactions that happens in glycolysis |
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Approximately how many moles of ATP will be generated as a result of the oxidation of one mole of FADH2 in an actively respiring mitochondrion?
A) 0 B) 2.0 C) 3.0 D) 4.5 E) 6.0 |
B
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If a subcellular fraction from liver tissue exhibits a high level of acid phosphatase activity, it most likely contains
A) nuclei B) lysosomes C) endoplasmic reticulum D) coated vesicles E) mitochondria |
B
you know it's lysosome because in the question is said high level of acid phosphate. High level of acid phosphate is needed for protein degradation. |
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Evidence indicating that chloroplasts were originally free-living prokaryotes that subsequently evolved a symbiotic relationship with a eukaryotic host includes all of the following EXCEPT the
A) similarities of rRNA sequences between chloroplasts and free-living prokaryotes B) similarities in structure between chloroplasts and some contemporary free-living prokaryotes C) presence of circular DNA in chloroplasts and in free-living prokaryotes D) susceptibility of chloroplasts to inhibitors of prokaryotic protein synthesis E) ability of chloroplasts to synthesize all their own proteins |
E
Ability of chloroplasts to synthesize all their own proteins |
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Which of the following is NOT a characteristic of intermediate filaments?
A) They form the nuclear lamina B) They provide mechanical stability to animal cells C) Their protein composition is tissue specific D) They are composed of globular monomers that polymerize to form fibers E) They include the keratin filaments of epithelial cells. |
D
Intermediate filaments are like a rope. It is formed with fibrils and fibrils twisted together to form intermediate filaments. |
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The amino acid sequence of a novel membrane protein contains four immunoglobulin-like domains and six fibronectin-like repeats. This protein is most likely a
A) cell adhesion molecule B) hormone-responsive ion channel C) G protein D) protein-serine/threonine kinase E) transcription factor |
A
Cell Adhesion Molecules (CAMs) are proteins located on the cell surface involved with the binding with other cells or with the extracellular matrix (ECM) in the process called cell adhesion. The selectins, integrins and cadherins are a family of CAM. |
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Which of the following is correct concerning the evolution of photosystem II in cyanobacteria?
A) It made Photosystem I in these organisms unnecessary for photosynthetic fixation of carbon dioxide B) It provided these organisms with an almost inexhaustible supply of electrons from water. C) It allowed these organisms to use any electron donor to replace electrons lost from excited chlorophyll a molecules D) It allowed photochemically produced ATP to be exported to the cyotplasm E) It allowed these organisms to generate ATP for the fixation of carbon dioxide into sugars withou chemiosmosis. |
B
Cyanobacteria are the only group of organisms that are able to reduce nitrogen and carbon in aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). |
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Which of following sequences of events occurs when E. coli are released from catabolite repression by transfer to low-glucose medium?
A) cAMP levels rise, cAMP binds to CAP, cAMP-CAP complex binds to a site on DNA and activates transcription. B) cAMP levels rise, cAMP binds to CAP, cAMP-CAP complex binds to a site on DNA and represses transcription. C) cAMP levels rise, cAMP binds to CAP, cAMP-CAP complex is removed from a site on DNA and activates transcription. D) cAMP levels fall, cAMP is removed from CAP, CAP binds to a site on DNA and activates transcription. E) cAMP levels fall, cAMP is removed from CAP, CAP binds to a site on DNA and represses transcription. |
A
In bacteria, the level of cAMP varies depending on the medium used for growth. In particular, cAMP is low when glucose is the carbon source. This occurs through inhibition of the cAMP-producing enzyme, adenylate cyclase, as a side effect of glucose transport into the cell. The transcription factor CRP (cAMP receptor protein) also called: CAP (Catabolite gene Activator Protein) forms a complex with cAMP and thereby is activated to bind to DNA. |
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The ability of yeast to produce invertase, an enzyme necessary to metabolize sucrose, was abolished by either of two mutations, m-1 and m-2, that arose spontaneouly in two separate yeast cultures. A heterozygote formed by mating m-1 mutant cells with m-2 mutant cells would be expected to restore the yeast's ability to produce invertase if m-1 and m-2 are
A) mutations of two separate nonallelic genes B) in the same complementation groups C) identical alleles of the same gene D) suppressible by the same suppressor E) both temperature-sensitive mutations |
A
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All of the following components of a retrovirus are encoded by the viral genone EXCEPT
A) matrix proteins B) viral RNA's C) capsid proteins D) envelope lipids E) receptor-binding proteins |
D
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Some viruses have increased the coding potential of their genome by
A) integrating into the host genome B) using host ribosomes for translation C) using alternative splicing sites D) using a degenerate triplet code E) covalently linking a protein to the genome |
C
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Which of the following is most likely to lead to a loss of gene function?
A) A missense mutation in the open reading frame B) A change from a TAA codon to a TAG codon in the coding region C) A change from T to C in the promoter region D) A frameshift mutation in the coding region E) A sequence change in the 3' untranslated region |
D
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The molar absorption coefficient (extinction coefficient) of NADH at 340 nanometers is 6,220 liters per mole per centimeter, whereas that of NAD at 340 nanometers is 0. What absorbance will be observed when light at 340 nanometers passes through a 1-centimeter cuvette containing 10-micromolar NADH and 10-micromolar NAD?
A) 0.031 B) 0.062 C) 0.124 D) 0.31 E) 0.62 |
B
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All of the following processes occur in the mitochondria of mammalian cells EXCEPT
A) fatty acid biosynthesis B) protein synthesis C) DNA synthesis D) beta oxidation of fatty acids E) the citric acid cycle |
A
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Rubisco catalyzes the carboxylation and also the oxygenation of ribulose 1,5-bisphosphate. The initial products of these reactions include which of the following?
I. Glyceraldehyde 3-phosphate II. 2-phosphoglycolate III. 3-phosphoglycerate A) I only B) II only C) III only D) I and II E) II and III |
E
2-phosphoglycolate is a useless product. It is also known as RuBP carboxylase/oxygenase. Phosphoglycolate is recycled back to chloroplast stroma as glycerate.2-phosphoglycolate is formed when O2 is bound to the active site. O2 is constantly competing with CO2 for the binding site. If CO2 is bound only 3-phosphoglycerate is produced. |
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Which of the following is meant by the statement that glucose and mannose are epimers?
A) one is an aldose and the other is a ketose B) One is pyranose and the other is furanose C) They are mirror images of each other D) They rotate the plane of light in opposite directions E) They differ only in the configuration about one carbon atom |
E
Epimer is a configuration change of stereoisomer. |
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A solution contains DNA polymerase I, Mg2+ salts of dATP, dGTP, dCTP and dTTP, and an appropriate buffer. Which of the following DNA molecules would serve as a template for DNA synthesis when added to this solution?
A) A single-stranded closed circle B) A single-stranded closed circle base-paired to a shorter linear strand with a 3'-terminal phosphate C) A single-stranded closed circle base-paired to a shorter linear strand with a 3'-terminal phosphate D) A double-stranded closed circle E) A blunt ended, double-stranded linear molecule with a 3'-terminal hydroxyl at each end |
B
DNA elongation is elongated at the 3' hyroxyl ends. |
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which of the following enzymes plays a direct role in the biosynthesis of collagen?
A) Prolyl hydroxylase B) Tyrosine hydroxylase C) choline oxidase D) Monoamine oxidase E) Tryptophan oxygenase |
A
Prolyl hydroxylase is needed to remove hydroxyl group from fibril so it can be twisted to form fibers. The removal of hydroxyl is in the ER. |
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Organized clathrin structures are typically associated with the
A) nuclear envelope and endoplasmic reticulum B) Lysosomes C) trans golgi network and plasma membrane D) extracellular matrix E) inner membrane complexes of mitochondria and chloroplasts |
C
Most of the transport happens in the golgi. After sorting and modifying the protein the protein is transported to the destination from golgi by forming a vesicle by clathrin pitching off. |
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If the M-phase promoting factor is injected into a Xenopus primary oocyte, which of the following occurs?
A) S phase begins B) The oocyte enters G0 C) Apoptosis beings D) The germinal vesicle (nucleus) breaks down E) Mitosis is completed |
D
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Actin filaments are found in all of the following EXCEPT the
A) flagella of bacteria B) sarcomeres of skeletal muscle cells C) stress fibers of fibroblasts D) microvilli of the intestinal brush border E) contractile ring of dividing animal cells |
A
flagella only contain microfilaments and it is surrounded by plasma membrane. |
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Which of the following does NOT make direct use of a pH or proton gradient?
A) Mitochondrion B) Chloroplasts C) Cyanobacterium D) Protozoan cilium E) bacterial flagellum |
D
Protozoans (ciliates) possess motile cilia exclusively and use them for either locomotion or to simply move liquid over their surface. |
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A study is done on mammalin cell line that has a doubling time of 24 hours. These cells are synchronized in G1 and then labeled for 2 days with BrdU (an analog of thymidine that increases the density of DNA into which it is incorporated). At the end of the labeling period, chromosomal DNA is isolated from the cells and its density analyzed by equilibrium centrifugation in cesium chloride gradients. Which of the following patterns would be expected to be seen?
(H= Heavy, L= Light) A) 100% H/H B) 100% H/L C) 50% H/H, 50% H/L D) 50% H/H, 50% L/L E) 25% H/H, 50% H/L, 25% L/L |
C
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Which of the following statements is correct concerning a homeobox?
A) It is part of the promoter in eukaryotic genes that code for proteins involved in segmentation B) It is conserved protein structure found in glycolytic pathway enzymes C) It is a conserved protein structure found in tRNA-binding proteins D) It is conserved DNA sequence found in genes that code for proteins that regulate development E) It is a conserved DNA sequence found in genes that code for proteins that regulate homeostasis |
D
A homeobox is about 180 base pairs long; it encodes a protein domain (the homeodomain) which can bind DNA. |
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Which of the following best describes the function of the sigma subunit in the RNA polymerase of E. coli?
A) It is essential for elongation of the RNA transcript B) It is essential for the recognition of and binding to the promoter sequence C) It increases RNA polymerase binding to any DNA template D) It is required for transcription termination E) It keeps the core complex from dissociating |
B
Sigma subunit is a subunit located on RNA polymerase. It recognizes the promoter used in transcription for bacteria. Its alpha helix interacts with a sequence call Pribnow box or -10 region on the promoter site. |
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When Bacteriophage lambda infects a sensitive bacterium, one of the first messenger RNA species synthesized is very short, beginning at a site PL and extending just through an adjacent gene N. After the appearance of the gene N protein, messages become much longer, still beginning at PL but extending far beyond gene N. The N gene encodes
A) an antiterminator acting just beyong gene N B) a new sigma factor acting on a promoter beyond gene N C) an activator for a promoter beyond gene N D) an antirepressor that removes a protein repressor bound at gene N E) a protein that stabilizes the longer message |
A
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When the coding region of a prokaryotic gene is cloned into the lac Z downstream from the translational initiator, the chance of an in-frame fusion is
A) 1/2 B) 1/3 C) 1/5 D) 1/6 E) 1/9 |
D
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What is the pKa for trimethylammonium in water if the base ionization constant (Kb) for trimethylamine is 7.4 x 10^-5? (log 7.4 x 10^-5 = -4.13)
A) -4.13 B) 2.87 C) 4.13 D) 9.87 E) 11.13 |
D
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The source of oxygen for O2 production during photosynthesis by higher plants is
A) CO2 B) HCO3- C) H2O D) ATP E) chlorophyll |
C
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The rate-limiting step of fatty acid synthesis is catalyzed by
A) acetyl CoA carboxylase B) ATP-citrate lyase C) Malic enzyme D) pyruvate dehydrogenase E) Thiolase |
A
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Which of the following is true about the change in enthalpy (ΔH) of a reaction that is spontaneous at room temperature?
A) It is equal to TΔS B) It is positive and the reaction is exothermic C) It is negative and the reaction is endothermic D) It must be equal to zero E) It can be either positive or negative |
E
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Which of the following intermediate compounds is involved when a peptide is hydrolyzed by chymotrypsin?
A) An ester between the substrate's acyl carbon and the serine of the active site B) A thioester between the substrate's acyl carbon and the cysteine of the active site C) An amide between the substrate's acyl carbon and the lysine of the active site D) An amide between the substrate's acyl carbon and the asparagine of the active site E) An amide between the substrate's a-amino group and the aspartate of the active site |
A
Chymotrypsin hydrolyze ester bond and in the answer there is only one ester cleavage to choose from. |
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Heat-shock proteins were originally described as proteins produced in response to heat stress. Some are now known to act as
A) molecular charperones that regulate protein folding B) protein-tyrosine kinases C) Proteases that degrade ubiquitin-tagged proteins D) GTPase-activating proteins E) ionophores that dissipate H+ gradients |
A
hsp70 assist protein folding. |
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All of the following statements about the type-B cyclin proteins are correct EXCEPT:
A) Their presence is required for exit from mitosis B) They are present in cells during the G2 phase C) They are degraded via the ubiquitin pathway D) They activate the Cdc 2 kinase E) They are newly synthesized during every cell cycle |
A
Presence of Cyclin B is decreased when enter into M phase. Cyclin B rise during G2 phase. Cyclin binds to cdc2 in the G2 phase allowing the cells to enter into mitosis. |
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Which of the following is an advantage of confocal microscopy over conventional fluorescence microscopy?
A) The interaction of laser beam with the cell surface allows the imaging of individual macromolecules B) The use of electrons instead of light ot image the specimen results in greatly increased resolving power C) Optical section can be taken at different depths in a specimen D) Only scattered light enters the microscope lens, making the object appear illuminated against a dark background E) The inherent contrast of an unstained specimen is enchanced |
C
When I read the question, it said confocal microscopy so I thought of optical lenses. And the only answer that i think it's the closest to that would be the optical sections of different depths in a specimen. |
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Which of the following properties is common to all cytoskeletal motor proteins (such as kinesins, dyneins, and myosines)?
A) An actin-binding domain B) Two globular-head domains C) The ability to bind to biological membranes D) ATPase activity E) Two heavy chains and four light chain |
C
Kinesin transport cargo by walking unidirectionally along microtubule and it hydrolyze ATP. Kinesin walk toward the plus end. Dyneins does the same thing as kinesin but it walks toward the minus end of microtubule. It causes sliding on cilia and flagella. Myosin is involve in skeletal contraction. It binds to actin and ATP generate the walking movement of contraction. |
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Which of the following is NOT involved in the processing of mRNA precursors in eukaryotic cells?
A) Capping of the 5' end B) addition of poly A C) Excision of introns D) Splicing of exons E) Transport of the pre-mRNA to the cytoplasm |
E
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DNA polymerase contains a lysine residue that is important for binding to DNA. Mutations were found that converted this lysine to either glutamine, glycine, valine or arginine. Which mutations would be predicted to be the most and least harmful to the ability of the enzyme to bind DNA?
Most Least A) Valine Aspartate B) Glycine Arginine C) Arginine Glycine D) Glutamate Valine E) Glutamate ARginine |
E
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A mammalian zygote resulted from the fusion of a normal gamete with a gamete that formed after a nondisjunction event in one chromosome during meiosis II. Which of the following best describes the zygote?
A) Diploid B) Haploid C) Aneuploid D) Polyploid E) Polysomic |
C
Aneuploid is including the chromosome that is not duplicated. Polyploid is the condition of some biological cells and organisms manifested by the presenece of more than two homologous sets of chromosomes. |
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The specialized structures located at the ends of eukaryotic chromosomes are called
A) Terminators B) Telomeres C) Long terminal repeats (LTR's) D) centromeres E) Kinetochores |
B
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Black body, flat wings: 12.5%
Black body, curved wings: 37.5% Yellow body, curved wings: 12.5% Yellow body, flat wings: 37.5% A homozygous male fruit fly with black body color and curved wings is crossed with a virgin homozygous female fruit fly with yellow body color and flat wings. All the offspring of this cross display yellow body color and flat wings. If a virgin female selected from these offspring is mated to a homozygous male fruit fly with black body color and curved wings, four types of offspring will occur in the proportions shown above. Which of the following conclusion can be drawn about the nature of inheritance on the basis of these data? A) Black body color and curved wings are dominant over yellow body color and flat wings B) The results do not fit the typical 9:3:3:1 ratio, making this an example of multiple allelic inheritance rather than a normal dihybrid cross C) Recombinant types of offspring, as in this case, appear more frequently than do parental types D) These genes for body color and wing shape are independently assorting from each other E) These genes for body color and wing shape are linked |
E
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A bacterial protein-coding gene contains a terminator codon in the middle of the coding region, yet expression of the gene in the bacterium produces a functional protein. Translation of the gene probably requires
A) The excision of an intron B) a suppressor tRNA C) ribosomes that lack 5S RNA D) an mRNA with no ribosome binding site E) an mRNA with no secondary structure |
B
Since the terminator codon is not an intron so the answer with excision of introns can not be the correct answer. Suppressing the tRNA stops the translation being terminated. |
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Which of the following is NOT a potential problem associated with expressing a eukaryotic, protein-coding nuclear gene in prokaryotic cells?
A) Lack of an intron-splicing mechanism in prokaryotes B) Differences in the translation initiation codons used by eukaryotic cells and prokaryotic cells C) Susceptibility of the protein product to prokaryotic proteases D) Stability of mRNA in prokaryotic celss E) Differences in transcriptional signals between eukaryotic cells and prokaryotic cells |
B
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Treatment of intact mitochondria with an uncoupler, such as 2,4-dinitrophenol, in the presence of ADP, Pi, succinate, and oxygen would have which of the following effects on the rates of electron transport and ATP synthesis? (+ = stimulation, o = no effect, - = inhibition)
Rate of rate of Electron transport ATP synth A) + + B) - - C) + - D) - + E) + o |
C
2,4-dinittrophenol is an uncoupler that oxidative phosphorylate by carrying protons across the mitochondria leading to a energy consumption but no ATP produced. |
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All of the following compounds are capable of forming hydrogen bonds with water EXCEPT
A) Methanol B) Acetamide C) methyl acetate D) ethanolamine E) hexane |
E
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A water-soluble globular protein is most likely to have the highest proportion of which of the following amino acid residues buried within its core?
A) Serine B) Histidine C) Isoleucine D) Glutamate E) Lysine |
C
Isoleucine is the only nonpolar amino acid in the answer. Serine and glutamate are both polar. Histidine and Lysine are both charged. |
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Hexokinase activity in a desalted cell extract can be measured in a spectrophotometric assay at 340 nanometers. In addition to buffer, Mg2+, and lysate, the reaction mixture should contain
A) Glucose, ATP, NADPH and excess glucose 6-phosphate dehydrogenase B) Glucose, ATP, NADP+ and excess glucose-6-phosphate dehydrogenase C) Glucose, ADP, NADP+ and excess glucose-6-phosphate dehydrogenase D) Glucose, ATP, NADP+ and excess 6-phosphogluconate dehydrogenase E) Glucose 6-phosphate, ATP, NADP+ and excess glucose 6-phosphate dehydrogenase |
B
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Which of the following processes is NOT an example of allosteric regulation?
A) regulation of phosphofructokinase activity by fructose 2,6-bisphosphate B) Inactivation of nitrogenase by ADP-ribosylation C) Regulation of the lac operon by allolactose in E. coli D) Catabolite repression by CAP in E. coli E) activation of second-messenger synthesis within a cell in response to receptor-ligand binding at the cell surface |
B
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Allosteric Regulator is a product that is produced by an reaction and this product can regulate an enzyme in that same reaction.
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Which of the following is closest to the pH of a solution that contains 5 millimoles per liter of H+ ions?
A) 1.2 B) 2.3 C) 3.7 D) 6.5 E) 7.5 |
B
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Although multiple disulfide bonds are possible during the formation of the tertiary structure of some secretory proteins, only the "correct" ones are found in the secreted product. This is primarily due to the fact that
A) incorrectly folded proteins are degraded by lysosomes B) processing and folding is continued in the endosomes C) a protein facilitates the formation of correct disulfide bonds in the endoplasmic reticulum D) only correctly folded proteins are translated in the endoplasmic reticulum E) arginine residues guide the proper positioning of disulfide bonds |
C
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actin filaments and microtubules share all of the following properties EXCEPT:
A) They are involved in cell motility B) They are intrinsically polar structures C) They are associate with motor proteins D) They are assembled from subunits that are heterodimers E) They can be cross-linked into bundles |
D
Microtubules are polymers of α- and β-tubulin dimers. |
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The recognition site of the restriction endonuclease AvaI is CPyCGpuG where Py is any pyrimidine and Pu is any purine. What is the expected average distance, in nucleotide pairs, between AvaI cleavage sites in a random DNA sequence?
A) 4,096 B) 1,024 C) 682 D) 64 E) 6 |
B
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In a bacterial cell, a mutation in an aminoacyl-tRNA synthetase leads to charging of the entire tRNA ser population with alanine. Which of the following describes the result of using these aminoacyl tRNAs for protein synthesis in the cell?
A) The alanyl-RNA ser will not function in protein synthesis B) Protein synthesized using the alanyl-tRNA ser will contain neither alanine nor serine. C) Proteins synthesized using the alanyl-tRNA ser will contain only serine where alanine would normally occur. D) Proteins synthesized using the alanyl-tRNA ser will contain only alanine where serine would normally occur E) proteins synthesized using the alanyl-tRNA ser will randomly contain either alanine or serine where serine would normally occur |
D
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Which of the following matings between E. coli strains would result in a high frequency of transfer of chromosomal genes?
A) F+ x F+ B) F+ x F- C) F- x F- D) Hfr x Hfr E) Hfr x F- |
E
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In genetics, suppression of mutation refers to
A) restoration of the original phenotype due to a second mutation B) restoration of the original DNA sequence by mutation C) Prevention of expression of the mutant gnee by metabolic regulation D) appearance of the recessive phenotype in a heterozygous lipid E) inactivation of the gene by methylation |
A
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Which of the following pairs of compounds are interconvertible in the liver by a single polypeptide chain containing two different catalytic sites?
A) Glucose and glucose 6-phosphate B) 3-phosphoglycerate and phosphoenolpyruvate C) phosphoenolpyruvate and pyruvate D) Fructose 6-phosphate and fructose 1,6-bisphosphate E) fructose 6-phosphate and fructose 2,6-bisphosphate |
E
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In terms of energy yield, phosphorolysis is preferable to hydrolysis in the breakdown of glycogen or starch because
A) most phosphorylases have lower Km value than do the corresponding phosphatases B) glucose 1-phosphate yields more ATP than does free glucose when subsequently catabolized to pyruvate C) the products of hydrolysis cannot be metabolized by the glycolytic pathway D) the abundance of inorganic phosphate in the cell ensures that the reaction will function in the degradative and not the synthetic direction E) the debranching process requires phosphorylated glucose residues |
B
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which of the following six-membered ring compounds has the most planar structure?
A) Glucose B) Cytosine C) Cyclohexane D) Inositol E) Mannose |
B
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Substrate-level phosphorylation in the citric acid (Krebs) cycle depends directly on the energy of the
A) Thioester bond of succinyl CoA B) oxidative decarboxylation of isocitrate to α-ketoglutarate C) formation of citrate from oxaloacetate and acetyl CoA D) FAD-dependent oxidation of succinate to fumarate E) phosphoanhydride bond of 1,3-bisphosphoglycerate |
A
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All of the following are known to involve a Ca2+ activated, vesicle-mediated secretory event EXCEPT
A) synaptic transmission B) elevation of the fertilization membrane of the sea urchin C) release of histamine from mast cells D) sperm acrosomal reaction E) constitutive secretion of collagen |
E
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A mutant cell whose cilia lack central pair microtubules and radial spokes would be unable to perform which of the following cilia-associated processes?
A) ATP hydrolysis B) Bend propagation (beating) C) Outer doublet microtubule sliding D) Ciliary regeneration E) Proper length control |
B
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Labeling of mesoderm with vital dyes in the bertebrate embryo would result in labeling of which of the following adult tissues?
I. Neural II. Intestinal epithelial III. Skeletal muscle A) I only B) II only C) III only D) I and II E) II and III |
C
Intestinal epithelial is an endoderm |
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Deletion 1: Genes bde are lost
Deletion 2: Genes ac are lost Deletion 3: genes abd are lost The genes abcde are determined to be closely linked on the E. coli chromosome. Three random short deletions are created in the region, resulting in the removal of various genes are shown above. Which of the following gene orders is possible based on the deletion analysis? A) abcde B) acbed C) bdeac D) cadbe E) eacdb |
D
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Temperate bacteriophages differ from other bacteriophages in that temperate bacteriophages
A) reproduce at moderate temperatures B) inhibit synthesis of host-cell proteins C) fragment the host-cell chromosome D) can lysogenize the host cell E) lyse the host cell |
D
the lysogenic cycle does not result in immediate lysing of the host cell. Those phages able to undergo lysogeny are known as temperate phages. Their viral genome will integrate with host DNA and replicate along with it fairly harmlessly, or may even become established as a plasmid. |
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Which of the following is the most likely mechanism for the origin of multigene families?
A) Endosymbiosis B) Gene duplication C) convergent evolution of dissimilar genes D) Horizontal gene transfer E) Viral infection |
B
Multigene families occur when several similar genes exist in multiple copies in the same region of DNA. They are very similar and may differ by a few nucleotides. They occur in clusters and differ from tandem clusters. They are speculated to have come from unequal crossing overs in meiosis. they have homologies with singlegene families |
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Which of the following are found oly in organisms containing polycistronic mRNA?
A) Missense mutations B) Polar mutations C) Temperature-sensitive mutations D) Alternative splicing sites E) Deletion mutations |
B
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Which of the following is NOT required for Rec-A dependent recombination between two DNA molecules?
A) Strand Migration B) Ligation C) Mismatch repair D) Nuclease digestion E) DNA synthesis |
C
RecA is needed to preform holliday junction and RecA is used to fix mismatch mutation. It is only used to migrate DNA, ligate, DNA synthesis and digestion. |
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Which of the following occurs as result of epinephrine binding to its receptor?
A) cAMP is produced from AMP B) glycogen accumulates C) Phosphorylase kinase is phosphorylated and glycogen synthase is dephosphorylated D) Phosphodiesterase is activated to prolong the effect of cAMP E) A phosphatase inhibitor is activated by phosphorylation |
E
Epinephrine is a "fight or flight" hormone which is released from the adrenal glands when danger threatens. When secreted into the bloodstream, it rapidly prepares the body for action in emergency situations. The hormone boosts the supply of oxygen and glucose to the brain and muscles, while suppressing other non-emergency bodily processes (digestion in particular). |
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Hepatocytes are incubated for 2 hours in physiological medium containing 1 millimole of acetate with 500,000 disintegrations per minute (dpm) of [1-14C] acetate. If fatty acids extracted from the hepatocytes contain 5000 dpm, what is the rate of incorporation of acetate into fatty acid, in micromoles per hour?
A) 1.25 B) 2.50 C) 5.00 D) 10.00 E) 20.00 |
C
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pyruvate kinase transfer a phosphate group from phosphoenolpyruvate to ADP, forming pyruvate and ATP. The reaction catalyzed by this enzyme is essentially irreversible. Which of the following is the best explanation for the irreversible nature of this reaction?
A) The binding of pyruvate to the active site is very eak relative to the binding of phosphoenolpyruvate B) the reaction is coupled to the pyruvate dehydrogenase reaction C) the hydrolysis of ATP is highly favorable D) The change in free energy (ΔG') for the overall reaction is large and negative E) There is a different enzyme is the cell which synthesizes phosphoenolpyruvate |
D
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Activation of amino acids for peptide synthesis utilizes ATP, generating pyrophosphate, rather than Pi, as a product. The metabolic advantage of producing pyrophosphate rather than Pi is the
A) hydrolysis of the α-β phosphodiester linkage releases more energy than does hydrolysis of the β-γ linkage B) ATP is readily resynthesized from the product AMP by the adneylate kinase reaction C) subsequent pyrophosphate hydrolysis by pyrophosphatase pulls the reaction in favor of the product D) the interaction of groups on the enzyme surface with the β phosphate as well as the γ phosphate makes removal of pyrophosphate faster E) the pyrophosphate ion buffers over a wider range than phosphate |
C
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During cytokinesis in plant cells, the cell plate is formed by the fusion of vesicles derived from which of the following?
A) Microtubules B) The Golgi complex C) The contractile ring D) The plasma membrane E) The cell Wall |
B
Read question more carefully.. it asked where did the cell plate formed by the fusion of the vesicles from. |
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Which of the following is NOT a property of the mammalian signal recognition particle (SRP)?
A) It targets nascent secretory polypeptides to the rough endoplasmic reticulum B) It temporarily arrests translation C) It binds to the signal sequence of secretory proteins D) It contains both RNA and several polypeptides E) It contains a signal peptidase activity |
E
he signal recognition particle (SRP) is a protein-RNA complex that recognizes and transports specific proteins to the endoplasmic reticulum in eukaryotes and the plasma membrane in prokaryotes. The SRP is found in the cytosol. In eukaryotes, it binds to the endoplasmic reticulum signal sequence found in an emerging secretory protein and subsequently delivers the protein along with the ribosome creating it to the endoplasmic reticulum membrane. When SRP binds the endoplasmic reticulum signal sequence, it also binds the ribosome and thereby pauses translation until the entire SRP-bound translation complex is transported to the endoplasmic reticulum, where translation resumes. |
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The ribosome is involved in all of the following EXCEPT
A) peptide bond formation B) aminoacylation of tRNA C) binding of protien factors during elongation D) binding of aminoacyl tRNA to mRNA E) binding of mRNA at an initiation codon |
B
ribosome does not involve aminoacylate tRNA It is only used to synthesize protein by binding to mRNA |
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An E. coli strain lacking DNA polymerase I would be deficient in DNA
A) repair B) methylation C) splicing D) degradation E) transcription |
A
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In a mating between two strains of yeast that differ at a single locus (wild type x mutant), 15 percent of the tetrads contain wild-type and mutant spores in the ratio of 3:1 or 1:3. The most likely explanation for this observation is
A) gene conversion B) deletion of the mutant allele C) allelic exclusion D) codominance E) reversion |
A
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The expression of the trp operon in E. coli is regulated in part by the availability of the amino acid tryptophan. This regulatory process is referred to as
A) attenuation B) translational read-through C) alternative splicing D) antitermination E) nonsense supprssion |
A
At the beginning of the transcribed genes of the trp operon is a leader sequence, which codes for a very short polypeptide. Near the end of this sequence, two tryptophans are coded for next to each other. Because tryptophan is a fairly uncommon amino acid,this is highly unusual. Since in prokaryotes the ribosomes begin translating the mRNA as soon as the RNA polymerase has moved farther down the DNA sequence, upstream translation occurs simultaneously with transcription of downstream genes. So, as soon as the polymerase has created the mRNA for the leader sequence, it is being translated. When the ribosome reaches the double-trp codons, if enough trp is present, the ribosome will not be delayed, and will continue translating until it reaches the stop codon and falls off the leader transcript. |
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which of the following types of information CANNOT be determined from the traditional Northern blotting technique?
A) The size of an mRNA species B) the Half life of an mRNA species C) The strand of DNA that is transcribed into mRNA D) The amino acid sequence of the protein coded by an mRNA species E) The relative levels of an mRNA species in different tissues |
D
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DNA sequence rearrangements are involved in all of the following processes EXCEPT
A) immunoglobulin gene expression in mammals B) transposition of bacteriophage Mu C) mating-type switching in trypanosomes D) intron splicing in ciliates |
E
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Which of the following elements is LEAST likely to be found on any + strand viral genomic RNA?
A) A cap B) A packaging site C) A binding site for RNA-dependent RNA polymerase D) A binding site for ribosome E) A binding site for RNA polymerase II |
E
At the beginning of the transcribed genes of the trp operon is a leader sequence, which codes for a very short polypeptide. Near the end of this sequence, two tryptophans are coded for next to each other. Because tryptophan is a fairly uncommon amino acid,this is highly unusual. Since in prokaryotes the ribosomes begin translating the mRNA as soon as the RNA polymerase has moved farther down the DNA sequence, upstream translation occurs simultaneously with transcription of downstream genes. So, as soon as the polymerase has created the mRNA for the leader sequence, it is being translated. When the ribosome reaches the double-trp codons, if enough trp is present, the ribosome will not be delayed, and will continue translating until it reaches the stop codon and falls off the leader transcript. |
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Largely insoluble in aqueous solution
A) NaCl B) Glucose C) Valine D) Polyadenylate E) Cholesterol |
E
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Highly soluble in water and solvated entirely by hydrogen bonding
A) NaCl B) Glucose C) Valine D) Polyadenylate E) Cholesterol |
B
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Forms hydrated ion pairs in aqueous solutions
A) NaCl B) Glucose C) Valine D) Polyadenylate E) Cholesterol |
A
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Exists largely as a zwitterion (dipolar ion) in aqueous solutions at neutral pH
A) NaCl B) Glucose C) Valine D) Polyadenylate E) Cholesterol |
C
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Stabilized by base-stacking
A) NaCl B) Glucose C) Valine D) Polyadenylate E) Cholesterol |
D
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Site of synthesis of histone mRNA
A) Nuclear envelope B) Nucleolus C) Euchromatin D) Heterochromatin E) Nuclear Lamina |
C
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Site of transcriptionally inactive DNA
A) Nuclear envelope B) Nucleolus C) Euchromatin D) Heterochromatin E) Nuclear Lamina |
D
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Site of Protein synthesis
A) Nuclear envelope B) Nucleolus C) Euchromatin D) Heterochromatin E) Nuclear Lamina |
A
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Site of transcription by RNA polymerase II
A) Nuclear envelope B) Nucleolus C) Euchromatin D) Heterochromatin E) Nuclear Lamina |
C
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Site of 45S rRNA processing
A) Nuclear envelope B) Nucleolus C) Euchromatin D) Heterochromatin E) Nuclear Lamina |
B
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A Mammalian peroxisomal enzyme
A) Aconitase B) Arginase C) Catalase D) Allantoinase E) Asparaginase |
C
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A citric acid (Krebs) cycle enzyme
A) Aconitase B) Arginase C) Catalase D) Allantoinase E) Asparaginase |
A
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A urea cycle enzyme
A) Aconitase B) Arginase C) Catalase D) Allantoinase E) Asparaginase |
B
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An enzyme of purine nucleotide catabolism
A) Aconitase B) Arginase C) Catalase D) Allantoinase E) Asparaginase |
D
Allantoine is a product of oxidation of uric acid by purine catabolism. |
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A Gene that segregates with maleness
A) Polygenic B) Holandric C) Polymorphic D) Epistatic E) Pleiotropic |
B
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A trait determined by the action of more than one gene
A) Polygenic B) Holandric C) Polymorphic D) Epistatic E) Pleiotropic |
A
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A gene that masks the expression of another gene
A) Polygenic B) Holandric C) Polymorphic D) Epistatic E) Pleiotropic |
D
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A gene that is present in a population in more than one form
A) Polygenic B) Holandric C) Polymorphic D) Epistatic E) Pleiotropic |
C
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A gene that has multiple phenotypic effects
A) Polygenic B) Holandric C) Polymorphic D) Epistatic E) Pleiotropic |
E
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The primary importance of phospholipids as constituents of cell membranes is related to the fact that they
A) are zwitterions B) combine covalently with proteins C) replace cholesterol D) contain diacylglycerol E) contain both polar and nonpolar regions |
E
Because Phospholipids are a form of phosphobilayer. To form a bilayer a polar and nonpolar region is needed. It can't be A because phospholipids are not zwitterions because it does not have a positive and negative charges. |
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The folded states of globular proteins in aqueous solutions are stabilized primarily by
A) hydrophobic interaction B) peptide bonds C) phosphoester bonds D) ionic bonds E) disulfide bridges |
A
In Aqueous, The apolar group would be folded inside the protein and the polar group would be expose on the outside of the protein. Therefore, the protein is folded by hydrophobic interactions. |
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The ionic strength of 0.5 molar MgCl2 is
A) 0.25 B) 0.5 C) 1.0 D) 1.5 E) 5.0 |
D
Ionic strength = 1/2 ∑CZ^2 |
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The most efficient substrate of an enzyme is usually considered to be the substrate with the
A) largest Vmax B) largest Km C) Largest Vmax/Km D) smallest Vmax/Km E) smallest kcat |
C
The most efficient substrate of the enzyme is considered to be the substrate with the largest Vmax/Km because Vmax value does not change |
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In the light reactions of photosynthesis, the terminal electron acceptor for noncyclic electron flow is
A) ATP B) NAD+ C) NADP+ D) water E) oxygen |
C
In the light reaction, an electron was lost and one proton was absorbed. This electon then undergo a electron transport chain which reduced NADP+ to NADPH. The Chlorophyll uses water to regain the electron lost in the light photosynthesis reaction and releases O2 as waste. In the dark reaction, Rubisco take up CO2 from the surroundings which is needed to form NADPH. This cycle is called Calvin Benson Cycle which release 3 carbon sugars which is later combined to glucose. |
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Which of the following is the most effective method for isolation of secretory vesicles from a cell lysate?
A) Ammonium sulfate precipitation B) Differential centrifugation C) Electron microscopy D) Reverse-phase high performance liquid chromatography (HPLC) E) Nuclear magnetic resonance (NMR) spectroscopy |
B
Differential Centrifugation is a method that uses centrifugation to spin the cell and seperate the homogenate and the cell by their mass. Ammonium sulfate precipitation is used only to purify protein. It is used to salt out high salt concentration protein. |
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Which of the following has NOT been demonstrated to be a function of the smooth endoplasmic reticulum?
A) Steroid hormone synthesis B) cholesterol synthesis C) Detoxification of lipid-soluble drugs D) sequestration of Ca2+ E) Addition of sialic acid to glycoproteins |
E
The function of smooth Endoplasmic reticulum 1.Storage of Ca++ 2.synthesis of lipids 3.metabolism of carbohydrates and calcium concentration 4.Attachment of receptor of cell membrane |
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Communication among th cisternae of Golgi complex is mediated by
A) endosomes B) microfilaments C) clathrin D) transport vesicles E) ionophores |
D
Transport vesicles is used to transport molecules from Rough ER to Golgi Apparatus. Clathrin is just a coat that forms vesicles. Ionophores are lipid solube molecules usually synthesized by microorganism to transport ions across the lipid bilayer. |
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The theoretical limitation of the resolving power of light microscopes depends on which of the following?
A) Intensity of the illumination B) Magnification of the objective lens C) wavelength of the incident light D) curvature of the lens E) spherical aberration |
C
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In neurons, inhibition of the Na+-K+ ATPase with ouabain will produce
A) slow depolarization B) slow hyperpolarization C) an action potential D) an inhibitory postsynaptic potential E) electrotonic current spread |
A
Inhibition of Na-K ATPase pump will produce slow depolarization because all the other pumps is still active to leak out molecules. |
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A cross between true-breeding red and true-breeding white snapdragons produces all-pink progeny. The relationship of the allele for red color to the allele for white color is best described as
A) epistatic B) complementary C) recessive D) dominant E) partially dominant |
E
partially dominant because of the mix of the gene gives another phenotype then the both parents. If the phenotype is the same as one of the parent's phenotype then the gene can be dominant or recessive depending on which gene is the dominant gene or recessive gene. Epistatic gene is an interaction between a nonallele genes especially an interaction in which one gene suppresses the expression of another. |
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A missense mutation in a cell is LEAST likely to result in the synthesis of a polypeptide that is
A) functionally normal B) shortened C) temperature-sensitive D) salt-sensitive E) immunologically cross-reactive |
B
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All of the following are major components found in transcriptionally active chromatin EXCEPT
A) hnRNA B) DNA C) histones D) nonhistone proteins E) lipids |
E
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A = 27% G = 30% T= 21% C = 22%
If the genome of a newly isolated virus displays the base composition above, the virus most likely consist of A) single-stranded DNA B) double stranded DNA C) single-stranded RNA D) double-stranded RNA E) a double-stranded DNA-RNA hybrid |
A
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Which of the following serves as the primer for the reverse transcriptase of a retrovirus such as HIV?
A) a specific host tRNA B) a specific host protein C) U6 snRNA D) U2 snRNA E) a virally synthesized piece of DNA |
A
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The pH of 10^-8 molar HCl solution prepared with pure water at pH 7.0 is closest to
A) 6.0 B) 6.9 C) 7.1 D) 7.9 E) 8.0 |
B
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Which of the following statements about the biosynthesis of cholesterol is INCORRECT?
A) Acetyl CoA is a substrate B) Acetoacetyl CoA is an intermediate C) Testosterone is an intermediate in the reactions D) Squalene is an intermediate product E) Mevalonic acid is formed at an early step of the synthesis |
C
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Which of the following reactions is catalyzed by nucleoside diphosphate kinase?
A) ATP + AMP <-> 2 ADP B) ATP + ATP <-> 2 ADP + 2Pi C) ATP + CDP <-> ADP + CTP D) ADP + CDP <-> CTP + AMP E) AMP + AMP <-> ADP + adenosine |
C
Nucleoside diphosphate kinase transfer one of the phosphate group to another nucleoside diphosphate. |
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When intramitochondrial coenzymes are oxidized by the mitochondrial electron-transport system, which of the following statements is correct about the yields of ATP?
A) FMNH2 and NADPH yield 3 and 2 ATP respectively. B) NADH and FADH2 yield 3 and 2 ATP respectively C) NADH and FADH2 yield 2 and 3 ATP respectively D) CoASH and FADH2 yield 2 ATP each. E) NADPH and FADH2 yield 3 ATP each |
B
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Appropriate disulfide-bond formation is crucial to the function of many protein hormones. Since for any particular polypeptide sequence many alternate disulfide bonds may form, which of the following mechanisms is mostly likely to promote formation of the most stable configuration?
A) Use of previously synthesized proteins as templates for disulfide location B) Hydrophobic interactions in the Golgi complex C) Thiophosphorylation during translation D) Bond rearrangement by protein disulfide isomerase in the endoplasmic reticulum E) Removal of side chain involved in inappropriate disulfide formation |
D
The Activity of Protein disulfide isomerase can be related to charperon. It forms disulfide bond between cystine. This enzyme act as a catalyze for protein folding. |
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Which of the following is a result of the cortical reaction after fertilization of a sea urchin egg?
A) Depolarization of the plasma membrane through sodium influx B) An increase in cytosolic calcium concentration through the release of ions from intracellular stores C) An increase in cytosolic pH through the action of a proton/sodium exchange system D) Activation of phospholipase C with an increase in inositol triphosphate levels E) Cross-linking of proteins in the vitelline layer causing it to harden |
E
The sodium influx and increase in calcium concentration only occur to block polyspermy in urchin. Sodium influx is increase the potential to 20mV from resting potential -70mV. This reaction is a fast block to polyspermy. The increase in calcium harden the vitelline layer by the increase in protein synthesis. This protein synthesis fuses the egg and sperm to form diploid embryonic nucleus. |
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Which of the following organelle/protein associations is LEAST likely to be observed in a eukaryotic cell?
A) Mitochondrion/cytochrome c B) plasma membrane/phospholipase C C) Golgi complex/galactosyl transferase D) Lysosome/cathepsin D E) Peroxisome/cytochrome f |
E
Cytochrome f is the largest subunit of cytochrome b6f complex. |
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A soluble, high-salt extract made from liver rough microsomes arrests the translation of preproinsulin mRNA but not of globin mRNA in vitro. The most likely explanation for this observation is that
A) globin is not synthesized in the liver B) insulin is a cytosolic protein C) the preproinsulin mRNA is degraded rapidly upon addition of the extract, but the globin mRNA is the most stable D) a component in the extract inhibits the translation of secretory proteins E) a sequence at the N-terminal end of globin promotes its translation in a cell free system, but this sequence is absent in preproinsulin |
D
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A protein kinase isolated from a certain eukaryotic species functions in an appropriate manner in cell-free systems that are derived from many other species. This suggests that which of the following a true of the gene that codes for this protein?
A) It has been highly conserved during evolution B) It has not been subjected to mutation C) It is expressed in cell-free system D) It must e a short length E) It need not be present in all organisms |
A
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Attenuation is a regulatory mechanism used by bacteria to respond to the concentration of
A) NADH B) ATP C) specific proteins D) specific amino acids E) specific phospholipids |
D
Attenuator refers to a regulatory sequence that forms into hairpin and stop translation. Attenuation is when the cell has produced too much of one amino acid, then the cell would not want to produce anymore so this region will be folded to avoid this region to be producing that amino acid. |
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Unequal crossing-over between homologous chromosomes is most likely to result in
A) translocation B) circularization C) inversion D) transposition E) duplication |
E
Uneven cross over does not affect duplication. Transposition a mutation in which a chromosomal segment is transferred to a new position on the same or another chromosome. |
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In the majority of higher plants, inheritance of chloroplast encoded traits occurs
A) from the maternal parent only B) from the paternal parent only C) equally from both parents (codominant) D) at varying ratios from both parents E) according to typical Mendelian segregation ratios |
A
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In the progeny from a cross involving an organism that produces unordered tetrads, linkage between two genes would be indicated primarily by
A) a preponderance of nonparental ditypes B) a preponderance of parental ditypes C) a tetratype frequently of less than 50% D) a parental ditype frequency of less than 50% E) equal numbers of parental ditypes, nonparental ditypes, and tetratypes |
B
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Glycogen is a polymer composed of which of the following?
A) Fructose B) Surcose C) Glucose D) Cellulose E) Galactose |
C
Glycogen is a storage form of glucose. When glucose is needed, the breakdown of glycogen is needed. |
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The amount of radioactivity remaining after a sample containing 1 microcurie of a radioactive isotope (t1/2 = 1 year) has decayed for five years is
A) 0.020 μCi B) 0.031 μCi C) 0.062 μCi D) 0.25 μCi E) 1.0 μCi |
B
t1/2 = 1 then t1/2 for 5 years = 1/32 1/32 * 1 = 0.03125 |
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S-> P
In the study of the first-order reaction above, the absolute value of the slope of a plot of the natural log (ln) of the concentration of S as a function of time is equal to which of the following? A) The first-order rate constant B) The second-order rate constant C) The Michaelis constant D) Initial velocity E) Activation energy |
A
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Which of the following statements about the migration of newly synthesized nuclear proteins into the nucleus is most accurate?
A) These proteins carry a signal sequence that targets them to nuclear pores, through which they enter the nucleus B) these proteins enter the endoplasmic reticulum, which is continuous with nuclear envelope, thus gaining entry into the nucleoplasm C) These proteins diffuse across the nuclear envelope at sites where the inner and outer membranes are in contact with on another D) these proteins are synthesized on ribosomes bound to the endoplasmic reticulum and are then recognized by specific polypeptides that transport them into the nucleus E) These proteins are synthesized on a specialized ribosomes that are bound to the nuclear envelope |
A
Newly synthesized nuclear protein into the nucleus is most accurate if these protein carry a signal sequence that targets them to the nuclear pores, through which they enter the nucleus. If a protein is target to be inside the nucleus would have signal that is recognized by the ER and the protein will be transfer back to the nucleus. |
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All of the following processes associated with protein synthesis can be mediated by eukaryotic mRNA's EXCEPT
A) recognition of aminoacyl-tRNA B) termination of translation C) release of initiation factors D) catalysis of peptide bond formation E) formation of polysomes |
D
The answer is the protein synthesis can be mediated by eukaryotic mRNA's EXCEPT catalysis of peptide bond formation. This answer is correct in this question because peptide bond formation has no direct interaction with the mRNA. Polysome is a complex of mRNA and a ribosome. |
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Neomycin directly interferes with the function of the phosphoinositide-specific phospholipase C and is most likely to interfere with transmembrane signaling pathways that involve activation of which of the following?
A) Adenylate cyclase B) Guanylate cyclase C) Tyrosine kinase D) Protein Kinase A E) Protein Kinase C |
E
Phospholipase C is an enzyme in phosphatidylinositol (PIP2). When PIP2 is hydrolyzed into two second messagers, inositol triphosphate and diacylglycerol which then modulate the activity downstream such as calcium level and protein kinase C. The answer can not be Protein kinase A because protein kinase A activity depend on cAMP level in the cell. The answer can not be Adenylate cyclase because it is an enzyme that catalyze ATP to cAMP. This enzyme can also activate or inhibit G protein. The answer can not be guanylate cyclase because it is an enzyme that catalyze GTP to cGMP. The answer can not be tyrosine kinase because this enzyme transfer a phosphate from ATP to tyrosine residue in a protein. |
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Which of the following statements is normally correct about mitochondria and chloroplasts?
A) They are fragments of cell nuclei B) They are reproduce in vitro C) they contain circular DNA D) They synthesize all their own proteins E) They can develop into new cells |
C
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After exocytosis, procollagen is converted into the extracellular matrix molecule collagen by which of the following posttranslational modification?
A) Proteopytic cleavage B) Formation of disulfide bonds C) addition of oligosaccharides D) Hydroxylation of proteins and lysines E) Removal of the signal sequence by signal peptidase |
A
Collagen is formed by cleavage of preprocollagen to procollagen to collagen. Collagen then form into collagen fibrils. Procollagen is transferred to golgi apparatus, where it is packaged and secreted by exocytosis. |
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All of the genes coding for enzymes in a prokaryotic biosynthetic pathway have conserved DNA sequences centered around position -10 and -35 before the initiation site of transcription. The Best explanation for this observation is that there is a binding site fore which of the following in these regions?
A) Rho factor B) DNA Polymerase C) RNA Polymerase holoenzyme D) DNA topoisomerase E) Ribosomes |
C
The answer can not be Rho factor because rho factor helps the termination of prokaryotic transcription. The answer is RNA Polymerase holoenzyme because this binds to a low affinity site to allow rapid exchange for an active promoter site when one opens. The -10 and -35 position is a promoter site upstream of the initiation site of transcription. |
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Which of the following best supports the concept of random inactivation of the X chromosome (Lyon hypothesis)?
A) Mosaicism in human females for X chromosome-encoded enzymes such as glucose 6-phoshpate dehydrogenase B) The transmittance of the X-linked disease hemophilia through the royal houses of Europe via the offspring of Queen Victoria C) The presence of only one X chromosome in women with Turner's syndrome D) The presence of a single Barr body in the interphase nuclei of the cells of human females E) The absence of a Barr body in the interphase nuclei of the cells of human males |
A
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The primary cause of aneuploidy in an organism is
A) Meiotic drive B) nondisjunction C) nonhomologous crossing-over D) double fertilization E) pericentric inversion |
B
Aneuploidy refers to when the chromosomes did not get separated in meiosis or mitosis. |
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During translation, an amino acid is attached to what part of the tRNA molecule?
A) A phosphoryl group on the 5' end B) A phosphoryl group on the 3' end C) A hydroxyl group on the 5' end D) A hydroxyl group on the 3' end E) A base on the 5' end |
D
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The bacteriophage φX174 has a single stranded DNA genome of 5,386 bases coding for 11 different proteins containing approximately 2,380 amino acid. The ability of this virus to exceed its apparent coding capacity is based on the fact that
A) its genome contains overlapping genes B) its amino acids are coded by base doublets rather than triples C) the cell's ribosomes translate each triplet more than once D) proteins are modified after their initial use E) different viral gene products are produced by protein splicing |
A
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Which of the following statements best describes isozymes?
A) They are catalytically active proteolytic degradation products of certain enzymes B) They are catalytically distinct enzymes of identical function C) they are enzymes that catalyze the same reaction and are present in more than one molecular form within the same species D) they are enzymes of identical function that are isolated from different species E) They are conformational isomers of multisubunit regulatory proteins |
C
Isozyme is an enzyme that catalyze the same reaction but they are different in their amino acid sequence. |
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Which of the following amino acids is the most soluble in water at pH 7.0?
A) glutamate B) Tryptophan C) Leucine D) Tyrosine E) Phenylalanine |
A
The answer is Glutamate. In this question, all other answer except glutamate and tyrosine would be eliminate because all other amino acids do not have an hydroxide group. Glutamate pKa = 4.1 and tyrosine pKa = 10.5. Glutamate is the answer because its pKa is closer to pH of 7. |
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Which of the following molecules binds strongly to avidin?
A) Pathothenic acid B) Folic Acid C) Methotrexate D) Niacin E) Biotin |
E
Avidin is a toxic protein in egg white that binds to biotin. Biotin is found in egg yolk. Avidin is a glycoprotein that has a very strong affinity that binds to biotin. |
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In assimilating inorganic compounds, plants are LEAST likely to reduce
A) carbon dioxide B) Nitrate C) nitrite D) phosphate E) sulfate |
D
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The portion of a transmembrane protein that is located within the plasma membrane is most likely to be composed of amino acids that are
A) acidic B) basic C) hydrophobic D) acetylated E) glycosylated |
C
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Which of the following best explains the massive disproportion in the number of sperm and ova produced by mammals?
A) Spermatogonia undergo more rounds of mitotic division preceding meiosis than do oogonia B) Spermatogonia proceed through more meiotic divisions than do oogonia C) Spermatogonia degenerate more easily than do oogonia D) Maturation of spermatogonia and oogonia is controlled by different pituitary hormones E) Nutrient availability is greater in the seminifernous tubules than in the germinal layer of the ovary |
A
Meiosis happens during fertilization. But producing sperm does not undergo Meiosis and producing eggs happens while fertilization. Therefore, spermatogonia undergo more rounds of mitotic division preceding meiosis than do oogonia. |
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All of the following statements about the plasma membrane of a typical mammalian cell are true EXCEPT:
A) Proteins and lipids are arranged asymmetrically across its plane B) Some proteins are capable of moving laterally within the plane of the membrane C) it has a fluid consistency at physiologic temperatures D) Its percentage of saturated lipids increases when the cell is grown at lowered temperatures E) Its carbohydrate content is small compared to its protein and lipid content |
D
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The process of gastrulation is essential to normal development because
A) cell size becomes variable B) three primary cell layer are formed C) the blastocoel is obliterated D) the antero postero axis is established E) the dorso ventral axis is established |
B
Gastrulation is development of embryo. Gastrulation follow by organogenesis, when individual organs develop within the newly formed germ layers. Gastrulation 3 layers are endodrem, ectoderm and mesoderm. Gastrulation think of stomach. 3 layers kind of like stomach, small intestine and large intestine. Although it does not have any relations but just an easy way to remember. |
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Dissociated vertebrate embryo cells normally reassociate according to the tissue of origin. Treatment of dissociated cells with trypsin prevents this reassociation. This suggests that which of the following is involved in cell-to-cell recognition?
A) Hormonal signaling B) Cellular positional memory C) Integrity of the lipid bilayer D) Differential gene activity E) Membrane glycoproteins |
E
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A human cell with 46 chromosomes is classified as
A) haploid B) tetraploid C) diploid D) triploid E) aneuploid |
C
Diploid cell has 46 chromosomes and haploid cell has 23 chromosomes. |
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All transposable elements contain specialized sequences of DNA that
A) facilitate recombination of the element within a replicon or between replicons B) facilitate recombination based primarily on DNA sequence homology C) code for DNA transfer from a donor to a recipient bacterium D) code for antibiotic resistance and transfer of chromosomal genes to recipient cells E) cause integration of a temperate phage into the genome |
A
Replicon is a single DNA or RNA that replicates from a single origin of replication. |
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Genetic maps constructed from recombination data do not always agree with genetic maps constructed by actual physical measurement because
A) physical maps are biased by multigene families B) physical maps are distorted by the frequency of gene conversion C) physical maps are defined by too few markers D) recombination data are distorted by the size of the genome E) recombination is influenced by chromosome structure |
E
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The lambda repressor protein and Cro protein recognize specific DNA sequence by using which of the following structures?
I. A stretch of antiparallel beta-pleated sheet II. A DNA binding fold with a helix turn helix motif III. a leucine zipper A) I only B) II only C) III only D) I and III only E) II and III only |
B
Leucine zipper is involve in regulating gene expression. |
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Studies of sex chromosomal abnormalities in humans indicate that sex determination is usually controlled by the
A) total number of X chromosomes B) presence of Y chromosome C) ratio of the number of X chromosome to the number of autosomes D) ratio of the number of Y chromosomes to the number of autosomes E) ratio of the number of X chromosomes to the number of Y chromosomes |
B
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Bacterial strain X is unable to grow unless the amino acid proline is added to the culture medium. A related strain Y is able to grow on the same medium without the addition of proline. when the cell free medium that was used to grow strain Y is mixed with strain X, a few ariant bacteria of strain X are subsequently found that no longer require proline for growth, even after multiple transfers to new medium that lacks proline. Which of the following statements best explains these observations?
A) Bacterial strain Y secretes proline into the growth medium B) bacterial strain Y secretes the enzyme for making proline into the medium C) bacterial strain Y transfers the genes for synthesizing proline to strain X bacteria by conjugation D) Bacterial strain X acquires the mRNA coding for the genes for synthesizing proline from strain Y. E) bacterial strain X acquires the genes for synthesizing proline from strain Y by transformation |
E
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The basis of precipitation of proteins by ammonium sulfate is best described by which of the following statements?
A) Proteins are rendered insoluble when they bind the ammonium ion. B) Proteins are rendered insoluble when they bind the sulfate ion C) addition of ammonium sulfate adjusts the pH to the isoelectric point of the proteins D) ammonium sulfate binds water molecules, making them less available for hydration of proteins E) Ammonium sulfate amidates carboxyl groups on the proteins, rendering the proteins insoluble |
D
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Which of the following explains why penicillin is toxic to many microorganisms?
A) It makes membranes excessively permeable to ions and permits K+ to leak out from cells B) It adheres to a component of the ribosome and prevents protein biosynthesis C) It hydrolyzes a polysaccharide and weakens the structural integrity of bacterial cell walls D) It inhibits the biosynthesis of folic acid and ultimately prevents DNA Replication E) It inhibits a transpeptidase and thus prevents cross-linking of peptidoglycans in the cell wall. |
E
penicillin binds to transpeptidase which is link to peptidoglycan then it weakens the cell wall. When it multiplies it will cause cell death |
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All of the following hormones can activate adenylate cyclase EXCEPT
A) glucagon B) testosterone C) epinephrine D) arginine vasopressin E) adrenocorticotropic hormone |
B
Glucagon binds to a G-protein that undergo an enzyme cascade which activates adenylate cyclase. Glucagon helps maintain glucose in blood. |
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Which of the following enzyme is localized in peroxisomes?
A) Cytochrome oxidase B) Cathepsin D C) catalase D) L-Latctate dehydrogenase E) Nitrogenase |
C
The function of Catalase is to catalyze the decomposition of hydrogen peroxide to water and oxygen. And this Catalase is located in peroxisomes. Peroxisomes in plants helps in photorespiration which uses oxygen to produce carbon dioxide and nitrogen fixation which break N2 to reactive nitrogen atoms. Cathepsin is a type of protein that breaks down other proteins a family of proteases. That is found in lysosomes. Lactate dehydrogenase has a function of interconversion of pyruvate and lactate. It is usually found in red blood cells. Nitrogenase is an enzyme that fix N2 gas. |
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Postranslational modification of newly synthesized secretory and plasma membrane proteins involves which of the following?
A) removal of the stop-transfer sequence B) Modification of N-linked oliosaccharides in the Golgi complex C) Addition of dolichol phosphate to the protein before it leaves the rough endoplasmic reticulum D) Secretion of binding protein (BiP) from the rough endoplasmic reticulum E) Activation of the peptidase that removes the KDEL sequence |
B
Protein synthesis Phosphorylation of oligosaccharides on lysosomal proteins removal of Man addition of GlcNAc addition of Gal addition of NANA sorting out to lysosome, plasma membrane and secretory vesicle |
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Which of the following is LEAST likely to cross the inner mitochondrial membrane?
A) Inorganic phosphate B) Malate C) Citrate D) Pyruvate E) NADH |
E
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H-Galactose is added to cultured fibroblasts in a 10-minute pulse and then chased with nonradioactive galactose. The cells are fixed and processed will autoradiography. The labeled galactose will concentrate first in which of the following area of the cell?
A) rough endoplasmic reticulum B) Smooth endoplasmic reticulum C) Plasma membrane D) Golgi complex E) nucleus |
D
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A mutant cell line taht lacks the gene for synthesis of the mannose 6-phosphate receptor would be expected to have which of the following characteristics?
A) An inability to modify O-linked oligosaccharides in the golgi complex B) Incorrect sorting of lysosomal enzymes C) An increase in receptor-mediated endocytosis D) AN increase in cytosolic concentration of mannose 6-phosphate E) Lack of fusion of transition vesicles from the endoplasmic reticulum with the cis Golgi |
B
The function of mannose 6-phosphate receptor is to increase level of phosphorylated lysozomal enzymes in body fluids secreted by thymocytes and fibroblasts. |
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Which of the following is correct concerning the acrosome of the mammalian speratozoon?
A) It provides ATP for motility B) It contains enzymes that facilitate penetration of the zona pellucida C) It contains buffers that neutralize the acidic pH of the female reproductive tract D) It promotes chromatin condensation E) It promotes fusion of the male and female pronuclei |
B
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Two oligo-deoxynucleotides 5'ACCACGTAACGGA3' and 5'GTTAC3' plus DNA polymerase are added to a reaction mixture containing the appropriate buffer plus dATP, dGTP, dCTP, and dTTP. The bases incorporated into the product of the reaction would have which of the following base composition?
A) 2C:1T B) 1G:1T C) 3G:2T D) 3G:3T:2C E) 5T:4G:3C:1A |
C
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A plasmid X is isolated from two strains of E. coli. It is observed that the plasmid isolated from one strain is easily digested by a certain restriction enzyme, whereas the plasmid isolated from the other strain cannot be digested by that enzyme. Which of the following best explains these observations?
A) The plasmid is methylated by one of teh strains but not by the other B) The plasmid is nicked in one of the strains but not in the other C) The plasmid from one strain is linear D) The enzyme-resistant plasmid must be double-stranded E) The enzyme-sensitive plasmid must be single-stranded |
A
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All of the following are posttranscriptional modification of hnRNA EXCEPT
A) capping of the 5' end B) poly A addition at the 3' end C) endonucleolytic cleavage to produce a new 3' end D) exonucleolytic cleavage to produce a new 5' end E) addition of O-methyl groups |
D
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Humans obtain nonessential amino acids via normal metabolism of α-keto acids by which of the following types of enzymes?
A) Aminotransferase B) Dehydratase C) Oxidase D) Decarboxylase E) Reacemase |
A
Aminotransferase removes the amino group from the amino acid which forms α-keto acid. |
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Which of the following bisphosphates is NOT an intermediate in the Calvin-Benson cycle?
A) Sedoheptulose 1,7-bisphosphate B) Glucose 1,6-bisphosphate C) Fructose 1,6-bisphosphate D) Ribulose 1,5-bisphosphate E) glycerate 1,3-bisphosphate |
B
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Which of the following is NOT a compound with high phosphoryl-group transfer capability?
A) ADP B) ATP C) AMP D) Acetyl phosphate E) Phosphohistidine |
C
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Protein-stabilization mechanisms include interactions of lysyl residues with side chains of
A) glycine B) arginine C) histidine D) aspartate E) asparagine |
D
Because Aspartate contains carboxyl group since lysyl residues contains a hydroxyl group. |
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Glucose 1-phosphate + UTP <-> UDP-glucose + PPi
The reversible reaction shown above is involved in glycogen synthesis. The reaction in the forward direction is driven in intact cells by the A) subsequent hydrolysis of PPi B) high concentration of glucose C) high concentration of UDP-glucose pyrophosphorylase D) low concentration of UDP-glucose E) high rate of dissociation of UDP glucose from the enzyme |
A
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In order for cytosolic palmitate (C16) to cross the inner mitochondrial membrane and gain access to oxidizing enzymes in the mitochondrial matrix, C16 is covalently linked to
A) acetoacetate B) 3-hydroxybutyrate C) glutathione D) carnitine E) glycerol |
D
Carnitine transport a long chain of acyl group from fatty acid into the mictochondria matrix so they can oxidized for energy. This fatty acid must be activated before binding to Carnitine to form acyl-carnitine. To activate the fatty acid in the cytosol, the fatty acid is attached to coA with a thioester bond. This reaction is catalyzed by the fatty-acyl-coA synthetase and driven to completion by inorganic pyrophosphate. Then the acyl group of the coA can now be transferred to Carnitine. In order to transport the acyl-carnitine into the mitochondria matrix, first the acyl-coA is conjugated to carnitine by carnitine acyltranferase located in the outer mitochondria. Secoond, the acyl carnitine is shuttled inside by translocase. Third, acyl-carnitine is transferred back to acyl-coA by carnitine acyltransferase located in the mitochondria matrix (palmitoyltransferase). Then the carnitine is transferred back out into the cytosol. |
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Radioimmunoassays are based on the principle of
A) competition between a radiolabeled ligand and an unlabeled ligand for binding sites on highly specific membrane receptor B) competition between two different radiolabeled ligands for binding sites on a highly specific antibody C) competition between a radiolabeled ligand and an unlabeled ligand for binding site on a highly specific antibody D) the ability of a radiolabeled ligand to elicit an immune response in a test animal E) the ability of a radiolabeled ligand to stimulate antibody production in vitro |
C
Radioimmunoassay involves mixing known quantities of radioactive antigens with antibody to that antigen, then add unlabeled or “cold” antigen and measuring the amount of labeled antigen displaced. |
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Target residues for protein kinases include which of the following?
I. serine II. Threonine III. Cysteine IV. Phenylalanine V. Tyrosine A) I and III only B) II and IV only C) III and V only D) I, II and III only E) I, II and V only |
E
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In a mature spermatozoan, the number of chromosome complements (n value) and the quantity of DNA present (c value) are expressed as 1n/1c. Which of the following is the correct expression of n and c in a primary spermatocyte? (assume that the primary spermatocyte has completed the premeiotic S phase, but has not yet completed the first meiotic division)
A) 4n/4c B) 2n/4c C) 2n/2c D) 2n/1c E) 1n/1c |
B
meiosis is the process that allow one dipole cell to divide in a special way to form two haploid cells. Meiosis is essentially for sexual reproduction. Mitosis is the process which a cell seperates its duplicated genome into two identical halves. Therefore in this primary spermatocyte is only undergo mitosis but not meiosis, which means that the chromosome did not get seperated and the DNA was duplicated but not divided since it only undergo S phase. |
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Which of the following distinguishes the constitutive secretory pathway from the regulated secretory pathway?
A) Proteins of the constitutive pathway are synthesized in lager precursor forms B) Constitutive vesicles are secreted selectively only during development C) Constitutive vesicles are, on average, larger than regulated vesicles D) Only constitutive vesicles derive from the trans Golgi networks E) Secretion is Ca2+ independent in the constitutive pathway |
E
Consitutive secretory pathway is when the proteins are secreted in response to a specific signal. The secretion of Ca++ is by a secondary messager. |
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Which of the following statements most accurately explains the identical response of adipose cells to glucagon and epinephrine in eliciting triglyceride breakdown?
A) The two hormones bind the same receptor in cytoplasm of the adipose cell B) The two hormones bind the same receptor on the plasma membrane of the adipose cell C) the two hormones bind the same receptor in the nucleus to alter gene expression D) The two hormones bind different receptors, but the receptors act through a common second-messenger system E) The two hormones have nearly identical chemical structures |
D
glucagon binds to glucagon receptor and it activates an adenylate cyclase. Adenylate cyclase manufactures cAMP which activates cAMP-dependent protein kinases. The enzyme activates phosphorylase B kinases. Phosphorlase B is an enzyme responsible for the release of glucose-1-phosphate from glucogen polymers. Epinephrine elevates blood sugar level by increasing catalysis of glucogen to glucose in liver. |
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The transverse tubule system of skeletal muscle provides
A) a pathway for discharge of K+ following contraction B) a pathway for electrical triggering of Ca2+ release from the sarcoplasmic reticulum C) sites where acetylcholine receptors are concentrated D) greater membrane area for active transport of Ca2+ into the sarcomere E) anchoring sites for actomyosin filaments |
B
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The mouse genome is about 650 times larger than the E. coli genome, yet the replication of the mouse genome takes only about 10 times longer than the replication of the E. coli genome. Which of the following best explains this observation?
A) Chromatin proteins accelerate the replication of the mouse DNA B) Not all of the mouse genome is replicated in a single cell cycle C) Mouse DNA is organized into chromosomes, whereas E. coli DNA is not D) Mouse DNA polymerase elongates DNA chains at a rate that is about 65 times that of E. coli DNA polymerase E) the mouse genome contains multiple origins of replication, whereas the E. coli genome contains only one. |
E
Prokaryotes have only one single origin of replication, but in eukaryotes there are multiple origin of replication. |
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Interphase cells from a variety of organisms, including dipteran insect, contain giant chromosomes that result from the occurrence of many cycles of DNA replication without the occurrence of strand separation or cytoplasmic division. These chromosomes may ave as many as 1,000-5,000 strands parallel to each other and are referred to as
A) pachytene chromosome B) multimeric chromosomes C) polytene chromosomes D) lampbrush chromosomes E) metaphase chromosomes |
C
Polytene chromosome undergo repeated rounds of DNA replication without cell divisions |
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The estrogen-responsive element (ERE) consists of the consensus sequence AGGTCAnnnTGACCT. Inversion of the ERE will most likely have which of the following effects on estrogen-dependent transcription of the genes that it controls?
A) Only a 3' gene will be turned off B) Only a 5' gene will be turned off C) Both 5' and 3' genes will be turned off D) There will be no change in the effect on either 5' or 3' genes E) All amino acids coded by the ERE will be changed |
D
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Proto-oncogenes may be converted to oncogenes by which of the following?
I. A point mutation within the open reading frame II. Deletion of part of the gene III. Integration of a retrovirus upstream from the open reading frame A) I only B) II only C) III only D) I and II only E) I, II and III |
E
Proto-oncogenes can be converted to oncogenes by A mutation in the proto-oncogene can cause a change in the protein structure A increase in protein concentration A chromosomal translocation |
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DNA replication in bacteria does NOT require which of the following?
A) A primer B) A template C) Deoxynucleotide triphosphates D) 5'->3' exonuclease activity E) Restriction endonuclease activity |
E
Restriction endonuclease an enzyme that cut a double stranded DNA. |
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Which of the following represents bonding interactions in order of strength from lowest to highest in buffered aqueous solutions?
A) Hydrogen, ionic, hydrophobic, covalent B) Hydrogen, hydrophobic, ionic, covalent C) Ionic, covalent, hydrogen, hydrophobic D) Hydrophobic, hydrogen, ionic, covalent E) Covalent, hydrophobic, hydrogen, ionic |
D
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In proteins targeted for degradation, the carboxyl terminal glycine of ubiquitin becomes covalently attached to which of the following?
A) Ornithine B) Arginine C) Lysine D) Histidine E) Glutamine |
C
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Which of the following compounds serves as the immediate sulfuryl (sulfate) donor for the biosynthesis of sulfate esters such as heparin, chondrotin sulfate, and cerebroside sulfate?
A) Inorganic sulfate B) Cysteine C) Glutathione D) S-adenosylmethionine (SAM) E) 3'-phoshpoadenosine 5'phosphosulfate (PAPS) |
E
Cysteine is involved in electron transfer reaction which help the enzyme catalyze it's reaction. Cysteine contains a sulphydryl group that can undergo redox reaction. Oxidation of cysteine can produce disulfide bond with another thiol or further oxidation can produce sulfonic acid. S-adenosylmethionine (SAM) is involved with transfer of methyl group in living cells. 3'-phosphoadenosine-5'phosphosulfate (PAPS) is a specific type of adenosine that is phosphorylated at the 3' and 5' position, with and addition sulfate group on the 5' phosphate. |
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Which of the following statements about the urea cycle is correct?
A) It is used to catabolize urea for energy B) It takes place entirely within mitochondria C) It converts a toxic waste product into a less toxic product for excretion D) It uses no cellular energy for converting ammonia into urea E) It uses the amino acid histidine as a critical intermediate |
C
Urea cycle can convert other substance like urea into something that is less toxic. Urea cycle happens in mitochondria and cytosol. |
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In the nitrogen assimilatory pathway, the nitrogen atom of ammonium is first found as the
A) amino nitrogen of glutamine B) Amino nitrogen of asparagine C) amido nitrogen of glutamine D) amido nitrogen of asparagine E) guanidinium nitrogen of arginine |
C
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Substrate-level phosphorylation is catalyzed by which of the following enzymes?
A) Hexokinase B) Succinyl-CoA-synthetase C) Citrate synthase D) Phosphofructokinase E) Phosphoribulokinase |
B
Hexokinase convert glucose to glucose 6-phosphate. Succinyl-CoA Synthetase catalyze the formation of succinate and coenzyme A. Succinyl-CoA synthetase catalyzes the reversible step in citric acid cycle, which involve the substrate level of phosphorylation of GDP. Citrate synthase is a pace-maker enzyme, as it controls the first step of Citric acid cycle (Krebs cycle). This enzyme is located in the mitochondrial matrix but the DNA of this enzyme is encoded in the nucleus. acetyl-CoA + oxaloacetate + H2O → citrate + CoA-SH Phosphofructokinase is important in glycolysis.This enzyme convert fructose 6-phosphate and ATP to fructorse 1,6-bisphosphate and ADP. Phosphoribulokinase converts ribulose 5-phosphate and ATP to ribulose 1,5 bisphosphate to ADP. |
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During receptor-mediated endocytosis, uncoupling of receptors and ligands subsequent to their inclusion in endosomes is caused by
A) dissociation of clathrin from the endosome B) dehydrogenation of NAD+ by complex I C) recycling receptors to the plasma membrane D) activation of lysosomal H+-ATPase E) acidification of endosomal contents |
E
Clathrin is used to bud off the endosome which transport substance into the vesicle for transport to another membrane. The endosomal compartment is usually acidic due to the action of a proton-pumping ATPase of the endosomal membrane. Many receptors involved in endocytosis of extracellular substances change their conformation at low pH and release their bound substance. The empty receptor proteins can then be sorted back to the cell surface. |
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Which of the following posttranslational modificiation is LEAST likely to occur during production of a soluble secretory protein?
A) Disulfide bond formation B) Glycosylation C) Proteolysis D) Myristorylation E) Hydroxylation |
D
Myristoylation is an irreversible process. Myristoylation plays a signal transduction and membrane targeting in plants. Glycosylation is a post-translational modification steps in the synthesis of membrane and secreted proteins in rough ER. Proteolysis is a direct degradation of proteins by cellular enzyme. |
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Which of the following experimental approaches was used to demonstrate nuclear protein targeting?
A) Determining the subcellular location of a nucleoplasmin-tubulin fusion proteins B) Determining the subcellular location of proteins containing the KDEL sequence C) Isolating mutants that are defective in topoisomerase genes D) Measuring the rate of histone entry during metaphase E) Injecting cAMP into the cell |
A
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Light absorbed by photoreceptor cells in the vertebrate retina increases the potential difference across to plasma membrane from -25 millivolts to -60 millivolts by
A) closing Na+ channels B) closing K+ channels C) closing Cl- channels D) opening Ca2+ channels E) opening HCO3- channels |
A
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All of the following occur in E. coli cells that are starved for amino acids EXCEPT
A) an accumulation of ppGpp B) an increase in overall mRNA synthesis C) an increase in protein degradation D) a significant reduction in tRNA synthesis E) a significant reduction in rRNA synthesis |
B
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If salivary gland cells of fruit flies are cultured in a medium containing 3H-uridine and then subjected to heat at 37˚C for 30 minutes, puffs appear along the length of the chromosomes at discrete spots that exhibit high levels of radioactivity. Thes puffs represent which of the following?
A) Areas of increase DNA replication B) The direct involvement of the chromosome in protein production C) regions of the chromosome that are undergoing abundant transcription D) Selectively denatured regions of the chromosome corresponding to heterochromatin E) The degradation of the chromatin in response to the heat shock |
C
The question said there is an radioactive Uridine and DNA does not contain Uridine therefore the answer A would not correct. Answer B does not seem correct either because the direct involvement of chromosome in protein production would have no relation with redioactive uridine. The answer D and E has no relation with uridine also. The only answer that relates to uridine is that uridine is needed for transcription. |
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Normal termination of RNA synthesis during bacterial transcription may be caused by which of the following?
I. RNA polymerase meets another polymerase moving in the opposite direction II. RNA polymerase passes a specific sequence in the DNA and falls off the DNA template III. RNA polymerase interacts with a specific protein and is removed from the newly formed RNA A) I only B) II oly C) III only D) I and II only E) II and III only |
E
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The failure of E. coli to produce β-galactosidase when it is grown in medium lacking glucose and containing lactose is most likely due to a nonsense mutation in the gene coding for the
A) α subunit of RNA polymerase B) sigma subunit of RNA polymerase C) catabolite activator protein D) lac repressor E) lac transacetylase |
Catabolite activator protein binds to DNA more tightly in presense of cAMP. cAMP level rise when the amount of glucose transport in the cell is low, but lactose is readily available.
Lac repressor is a DNA binding protein which inhibits the expression of genes coding for protein involves in the metabolism of lactose in bacteria. It is active when there is an absence of lactose. β-galactosidase transacetylase is an enzyme that transfer an acetyl group from acetyl CoA to β-galactosidases. Coded by the gene in the lac operon. |
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For mammalian fructose 1,6-bisphosphatase, fructose 2,6-bisphosphate is
A) a negative heterotropic effector B) a negative homotropic effector C) a positive heterotropic effector D) a positive homotropic effector E) not an effector |
A
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Which of the following statemtns about the mitochondrial ATP synthase complex is correct?
A) It is made up of 5 different polypeptides B) It is located entirely in the intermembrane space C) It is inhibited directly by dinitrophenol D) It translocates ATP across mitochondrial membrane E) It contains an F0 unit that function as a proton channel |
E
ATP-synthase is located in the inner membrane of mitochondrial. F1 contains 3 subunits and F0 contains 1 subunit. Oligomycin inhibit the ATP-synthase. ATP synthase does not tranlocates ATP across mitochondrial. It phosphorylate the ADP to ATP in the mitochondrial as protons are being pumped across the mitochondrial. |
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Which of the following is an example of regulation of an enzyme activity by reversible covalent modification?
A) Enolase + Mn2+ -> enolase (Mn2+) complex B) Preprocarboxypeptidase -> procarboxypeptidase C) Proinsulin -> insulin D) Isocitrate dehydrogenase + ADP -> isocitrate dehydrogenase·ADP E) Glycogen synthase a -> glycogen synthase b |
E
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During carbon flow from glucose to acetyl CoA in liver cells, all of the following function as regulatory enzyme EXCEPT
A) glucokinase B) phosphofructokinase C) triose phosphate isomerase D) Pyruvate kinase E) pryuvate dehydrogenase complex |
C
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In mammalian cells, the formation of malonyl CoA, the first intermediate in fatty acid biosynthesis, directly involves
A) biotin B) NAD+ C) NADP+ D) thiamine pyrophosphate E) folic acid |
A
Biotin is used in cell growth, the production of fatty acid, metabolism of fats and amino acids. |
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Which of the following statements is correct concerning ketone bodies (3-hydroxybutyrate and acetoacetate)?
A) They are breakdown products of nucleic acids B) They are carried in the blood bound to lipoproteins and albumin C) They are incorporated into fatty acids in the liver D) They are metabolized by most extrahepatic tissues E) they are not metabolized by brain cells |
D
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Which of the following is an important structural component of the erythrocyte cell membrane?
A) Lipopolysaccharide B) Cholesterol C) Hemoglobin D) Peptidoglycan E) 2,3-bisphosphoglyceric acid |
B
Cholesterol is a sterol and a lipid found in cell membrane of all body tissues, and transported in the blood plasma. Hemoglobin is the iron-containing oxygen transport metalloprotein in the red blood cells. Peptidoglycan serves as a structral role in bacterial cell wall. |
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The potential gradient across the chloroplast thylakoid membrane that results in the production of ATP is best described as a gradient of
A) Na+ and K+ B) Mg2+ C) Cl- D) Ca2+ E) H+ |
E
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All of the following statements are correct about the enhancer sequences of a gene EXCEPT
A) Their deletion usually results in a reduction in the rate of RNA synthesis from the gene B) They interact with DNA-binding proteins C) They increase the translation rate of the mRNA transcribed from the gene D) They are capable of stimulating transcription in an orientation-independent fashion E) They are sometimes found in viral genomes |
C
The enhancer sequence does not increase the RATE of translation. It only assist the polymerase to binds to the initiation site. |
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The thymidine analog 3'-azidothymidine (AZT) blocks replication of human immunodeficiency virus (HIV). AZT is converted in cells to the 5'-triphosphate derivative and then incorporated into a cDNA copy of the infecting HIV RNA by HIV reverse transcriptase. The cDNA terminates prematurely at the point of the inserted analog. The most likely reason that AZT is not equally inhibitory toward replication of human DNA is that the 5'-triphosphate derivative is
A) capable of base-pairing with riboadenosine in the HIV RNA, but not with deoxyadenosine in human DNA B) replaced with normal deoxynucleotide during mismatch repair C) unable to enter the nucleus, where DNA is replicated D) hydrolyzed by nuclear enzymes to thymidine-5'-triphosphate, so the azido form is not incorporated into replicating DNA E) bound with much lower affinity (resulting in a higher Km) to human DNA polymerase than to HIV reverse transcriptase |
E
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Upstream-activating sequences increase the expression of
A) the first downstream gene only B) the first upstream gene only C) all upstream genes only a range of several thousand base pairs D) all upstream and downstream genes within two hundred base pairs only E) all upstream and downstream genes over an extended region up to several thousand base pairs |
A
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All of the following statements about repetitive DNA segments in mammalian cells are correct EXCEPT
A) They occur only in nontranscribed regions of the genome B) they are occur as tandem repeats of short sequences of 5-10 nucleotides C) they can occur as thousands of copies of a 150-300 nucleotide sequence dispersed throughout the genome D) They can be present as families of similar, but not identical, nucleotide sequences E) They reassociate faster than unique-sequence DNA in hybridization experiments |
A
Repetitive DNA tend to have high frequency of nucleotides of adenosine and thymine. Satellite DNA consists of highly repetitive DNA. Satellite DNA has a short Tandem repeats. Tandem repeats are localized at telomeres and centromere. |
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Virus that utilizes reverse transcriptase for replication
A) Single-stranded linear RNA B) single-stranded linear DNA C) double-stranded linear DNA D) double-stranded covantly closed circular DNA E) Segmented double stranded RNA |
A
The question is virus that utilizes reverse trancriptase for replication and only RNA would need to use reverse transcriptase because it is needed to transcribe back to DNA. There are only 2 answers that would be right. It is between A or E. But the answer can not be E because segmented double stranded RNA could not use reverse trancriptase because it can not break the double strands. Therefore, A is the correct answer because it can transcribe a single stranded linear RNA. |
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Virus that can utilize theta replication
A) Single-stranded linear RNA B) single-stranded linear DNA C) double-stranded linear DNA D) double-stranded covantly closed circular DNA E) Segmented double stranded RNA |
E
Theta structure is an intermediate structure formed during the replication of a circular DNA molecule (prokaryote DNA). |
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Genes that are located on the same chromosome
A) Chiasmata B) Heterochromatic region C) Telomeres D) Synaptonemal complex E) Linkage group |
E
Linkage group is where genes that are located on the same chromosome. Genetic linkage occurs when particular alleles are inherited jointly. |
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The tripartile structure that forms between paired chromosomes just prior to the pachytene stage
A) Chiasmata B) Heterochromatic region C) Telomeres D) Synaptonemal complex E) Linkage group |
D
The synaptonemal complex is a protein that forms between two homologous chromosomes during meiosis and that is thought mediate chromosome paring, synapsis and recombination. The synaptonemal complex is a tripartile structure consisting of two parallel lateral regions and central element. |
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Structures on chromosomes that mark recombination events
A) Chiasmata B) Heterochromatic region C) Telomeres D) Synaptonemal complex E) Linkage group |
A
Chiamata are thought to be the point where two sister chromatids exchange genetic material during chromosomal crossover during meiosis. |
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Prohibits the diffusion of small metabolites and ions through intracellular spaces
A) Tight junction B) Gap Junction C) Spot demosome D) Hemidesmosome E) Adherens junction |
A
Tight junctions are closely associated areas of two cells whose membranes join together forming a virtual impermeable barrier to fluid. They care formed by claudin and oocludin proteins, joining cytoskeletons of the adjacent cells. They hold cells together and block movement of integral membrane proteins between apical and basolateral surfaces of the cell. They prevent the passage of molecules and ions through the space between the cells. |
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Allows direct intercellular signaling
A) Tight junction B) Gap Junction C) Spot demosome D) Hemidesmosome E) Adherens junction |
B
A gap junction is a junction between certain animal cell-types that allow different molecules and ions to pass freely between cells. The junction connects the cytoplasm of the cells. One gap junction is composed of two connexon which connect across the intercellular space. They are analogous to the plasmodesmata that join plant cells. |
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Attaches an epithelial cell to its underlying connective tissue
A) Tight junction B) Gap Junction C) Spot demosome D) Hemidesmosome E) Adherens junction |
D
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Prevents binding of the repressor protein to DNA
A) Corepressor B) Inducer C) Promoter D) Operator E) Open complex |
B
Inducers function by disabling reporessor proteins. Repressor proteins bind to DNA strand and prevent RNA polymerase from being able to attach to the DNA and synthesize mRNA. Inducers bind to repressor proteins, causing them to change shape and making them unable to bind to DNA. Therefore, allowing transcription and gene expression to take place. |
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Site on the DNA that binds a protein to turn transcription off
A) Corepressor B) Inducer C) Promoter D) Operator E) Open complex |
D
An operator is a segment of DNA which regulates the activity of the structural genes of an operon is link to, by interacting with a specific repressor or activator. It is regulatory sequence for shutting gene down or turn it on. A promoter is a DNA sequence that enables a gene to be transcribed. The promoter is recognized by RNA polymerase, which then initiates transcription. In RNA synthesis, promoter are a mean to demarcate which gene should be use for message RNA creation and controls which protein cell manufactures. Corepressor is a metabolite that bound to repressor forms functional unit that can bind to its operator and block transcription. |
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A component of photosystem I
A) P450 B) P700 C) pp60src D) 33P E) PII |
B
P700 is the reaction center chlorophyll a molecules associated with photosynthesis I. It absorption spectrum peak at 700nm. When photosynthesis absorbs light, an electron is excited to a higher energy level in the P700 chlorophyll. The resulting P700 with excited electron is called P700*. The electron is subsequently captured by the primary electron acceptor. The photosynthesis I uses ferredoxin-like iron sulfur clustor protein as terminal electron acceptors. P700 is a protein complex made of several subunits, that are mainly hydrophobic. P680 is the reaction center chlorophyll a molecules associated with photosynthesis II. Its absorption spectrum peak at 680nm. When photosynthesis absorbs light, an electron is excited to a higher energy level in P680 chlorophyll. The resulting P680 with excited electron is designated P680*. P680 is the strongest biological oxidizing agent known. |
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A cytochrome involved in drug hydroxylation
A) P450 B) P700 C) pp60src D) 33P E) PII |
A
Cytochrome P450 oxidase is a genetic term for a large number of evolutionary related oxidative enzymes, important in animal, plants and bacteria. Animal P450 are primarily membrane associated proteins, located either in the inner membrane of mitochondria or in the ER of the cells. In drug metabolism, P450 is probably the most important element of oxidative metabolism in animal. Metabolism in this context being the chemical modification or degradation of chemical including drugs and endogenous compounds. |
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A product of an oncogene
A) P450 B) P700 C) pp60src D) 33P E) PII |
C
Src is a family of proto-oncogene tyrosine kinase. The discovery of Src family proteins has been instrumental to the modern understanding of cancer as a disease where normally healthy cellular signaling has gone away. |
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ATPase responsible for microtubule sliding during flagellar bending
A) Tropomyosin B) Myosin C) Dynein D) Kinesin E) Flagellin |
C
Dynein is a motor protein in cells which converts the chemical energy contained in ATP into the mechanical energy of movement. Dynein transports various cellular cargo by walking along cytoskeletal microtubules toward the minus-end of the microtubule, which is usually oriented towards the cell center. Thus, they call this minus end directed motor while kinesin, motor proteins that move toward the microtubules' plus end, are called plus end directed motors |
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ATPase that has a role in cytokinesis
A) Tropomyosin B) Myosin C) Dynein D) Kinesin E) Flagellin |
B
Cytokinesis is the process whereby the cytoplasm of a single cell is divided to spawn to two daughter cells. Tropomyosin is an alpha helical coiled coil protein dimer. Tropomyosin blocks myosin binding and hence crossbridge cycling in the absence of Ca2+ and the muscle Ca2+ regulatory element troponin. |
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Used to oxidize disulfide bonds to cysteic acid residues
A) Cyanogen bromide B) Dansyl chloride C) Performic acid D) Iodoactate E) Urea |
C
Performic acid is a organic peracid used in cleaving disulfide links in peptides by oxidizing cysteine and cystine to cysteic acid. |
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Used in N-terminal amino acid analysis
A) Cyanogen bromide B) Dansyl chloride C) Performic acid D) Iodoactate E) Urea |
B
Dansyl Chloride is a strong fluorescent compound that will react with the terminal amino group of a protein. After acid hydrolysis of all the other peptide bonds, the terminal amino acid is identifiable as the dansylated residue. |
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Used to cleave peptide chains at methionyl residues
A) Cyanogen bromide B) Dansyl chloride C) Performic acid D) Iodoacetate E) Urea |
A
Cyanogen bromide is used to fragment proteins and peptides into smaller pieces. This is useful in the production of methionine-free peptides and for peptide mapping proteomics, since the process occurs exclusively at methionine residue. |
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Used to modify cysteine side chain to form thioethers
A) Cyanogen bromide B) Dansyl chloride C) Performic acid D) Iodoacetate E) Urea |
D
Iodoacetate is used in lab to bind covalently to cysteine, so the protein cannot aggregate to its natural structure. After that reducing agents are added to react any excess alkylating agent. It can cause skin tumor on laboratory mice, it can also act negatively to reproductivity. |
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Can lead to a dicentric chromosome after meiotic recombination
A) Amplification B) Excision C) Gene conversion D) Translocation E) inversion |
E
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Meiotic events that yeilds an unequal number of maternal and paternal alleles of specific locus
A) Amplification B) Excision C) Gene conversion D) Translocation E) inversion |
C
Gene conversion is phenomenon which occurs during meiotic division. It is a process by which DNA sequence information is transferred from one DNA helix to another DNA helix, whose sequence is altered. It occurs occasionally during general recombination. |
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Transfer of part of a chromosome onto another chromosome by breaking and joining
A) Amplification B) Excision C) Gene conversion D) Translocation E) inversion |
D
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