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80 Cards in this Set
- Front
- Back
What is used to classify prokaryotes?
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1. photosynthetic or nonphotosynthetic
2. motile or nonmotile 3. unicellular or colony-forming or filamentous 4 formation of spores or divison by transverse binary fission |
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A characteristic feature of the plasma membrane of prokaryotes is the prescence of what?
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invaginated regions
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Heterotrophs that harvest energy from organic molecules are called what?
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chemoheterotrophs
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Prokaryotes differ from eukaryotes in most characteristics besides what?
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The plasma membrane
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A microbiologist is investigating the effects of cold on a particular bacterium. He notices that as the temperature approaches zero degrees Centigrade, that the bacterium begins to
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form endospores
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Tuberculosis remains a serious world-wide health problem due to
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1. Transmission through the air
2. Social factors such as crowding and poverty 3. The increasing prevalence of HIV infections 4. It is multi-drug resistant |
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A microbiologist is conducting a research project on chemoautotrophs. This means that the investigator is examining certain aspects of a bacterium that
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can oxidize sulfur and other inorganic substances to get energy
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The disease sometimes referred to as the "silent STD" because it is usually asymptomatic in women early on is
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chlamydia
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Chancre is a sore that is formed due to
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nfection with Treponema pallidum
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Most viruses form a capsid around their nucleic acid core. This capsid is composed of
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a protein
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Virulent viruses multiply within infected cells and eventually
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cause lysis of the host cell, releasing new viruses
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The genetic alteration of a cell’s genome by the introduction of foreign DNA is called
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transformation
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Recently a class of infectious proteins with no associated nucleic acid, have been identified. They are referred to as
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prions
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The HIV virus is considered a ______ virus, because after getting integrated into the host cell chromosomes, it does not begin replicating immediately.
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latent
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Each HIV particle possesses a ___________ on its surface that precisely fits a cell-surface marker protein called CD4 on the surfaces of the immune system cells called macrophages and T cells.
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glycoprotein
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Phages are viruses which can infect
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bacteria
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Viruses that become established as stable parts of the host cell genome are called
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temperate
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The infection cycle of HIV includes what steps?
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attachment, entry into cells, replication, integration into the host cell's DNA, production of new viruses, and finally exit from the cells.
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The onset of AIDS is often accompanied by
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a steep drop in T cell numbers
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A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the
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envelope
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What are the major characteristics of viroids?
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1. Naked RNA molecules
2. Only a few 100 nucleotides long 3. Important infectious diseases in plants |
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Question 13 text Scientists have demonstrated that the cholera bacteria, Vibrie cholerae, exist in at least two forms. It usually exists in a rather harmless form, however a phage conversion can occur which produces a disease-causing, virulent form. This conversion is caused by
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the phage introducing a gene into the bacterium's chromosome that codes for the cholera toxin which can cause death in humans
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Viruses infect every organism that has been investigated for their presence. However, viruses can only replicate in
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a very limited number of the host’s cells
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Viruses may cause cancer by
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triggering the expression of cancer-causing genes present in the genome
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The _________________________ viruses have been linked with liver cancer in people with chronic infections.
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Hepatitis B and C
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Located on or within the cell are _________ proteins, each of which has a three dimensional shape complementary to that of a specific signal molecule.
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receptor
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The space into which neurotransmitters are released is called a chemical
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synapse
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Cyclic AMP and calcium ions are often used within a cell as
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secondary messengers
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The cells of multicellular organisms use a variety of molecules as signals which are
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proteins, individual amino acids, nucleotides, steroids, other lipids, and dissolved gases
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Signals with short-lived, local effects are called
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paracrine signals
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Synaptic signaling requires
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neurotransmitters
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The molecules that convert extracellular signals into intracellular ones are
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cell surface receptors
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Do chemically gated ion channels have genes incoded in them?
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No
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The class of cell surface receptors that act indirectly on plasma membrane-bound enzymes or ion channels are called
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G proteins
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A small number of surface receptors can ultimately generate a large intracellular response, as each step of the pathway is often expanded by
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signal amplification
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Most cells are in physical contact with other cells at all times by forming permanent connections called
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cell junctions
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In the digestive tract adjacent cells develop connections to form a sheet that prevents leakage of small molecules. These connections between cells are called
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tight junctions
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Small molecules or ions can pass from one cell to another through
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communicating junctions
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Junctions in which the cytoskeleton of a cell is attached to that of other cells or the extracellular matrix are called
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anchoring junctions
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A biochemist is designing a new drug that will mimic the shape of a particular signal molecule. She has to design the drug molecules so that they will be selected over the other “normal” molecules at the surface of the cell membrane. Therefore she must produce molecules that will bind to the receptor protein and
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induce a change in the receptor molecule shape, which will ultimately produce a cellular response
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What technique has recently aided the study of receptor proteins?
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monoclonal antibodies
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What occurs during autocrine signaling?
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Signal molecules are released from a cell and bind to receptors on its own plasma membrane.
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Intracellular receptors usually bind to
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lipid-soluble signals.
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What are the different types of cell surface receptors?
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chemically gated ion channels, enzymic receptors, and G-protein linked receptors
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What things are used as secondary messengers?
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cyclic adenosine monophosphate, calcium ions, and cAMP
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What does the amplification of a cellular signal require?
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a second messenger,a signal molecule, and a cascade of protein kinases
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MHC proteins are
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identity markers present on the surface of an individual's cells.
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Sheets of cells are formed from which type of cell junctions?
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tight junctions
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Cadherin can be found in what type of cell junction?
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anchoring junctions
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Plasmodesmata are a type of what junction?
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communicating junction.
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Viruses consist of a ________________ core surrounded by a protein coat.
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nucleic acid
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Phages infect bacterial cells by
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poking holes in the cell and injecting their DNA.
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The end result of the viral lytic cycle is
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the release of new viruses.
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The alteration of a cell's genome by the incorporation of foreign DNA is called
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transformation.
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What are the viral glycoproteins that play a role in the infection of human cells by HIV?
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CD4 and CCR5
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The HIV enzyme, ________________, produces a DNA copy of the viral genome once it is inside the host cell.
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reverse transcriptase
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The drug AZT and its analogs functions by
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inhibiting the replication of viral nucleic acid.
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What is the function of the CD8+ cell antiviral factor (CAF) in human white blood cells?
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blocks replication of the HIV virus
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New strains of flu viruses are most likely to arise in the Far East because
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common hosts (ducks, chickens, pigs) live in close proximity to humans.
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Which of the following infectious agents does not contain protein?
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viroids
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Once they evolved, _____________ forever changed the atmosphere on earth.
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cyanobacteria
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Are prokaryotic cells unicellular or multicellular?
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unicellular
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When bacterial cell walls are covered with an outer membrane of lipopolysaccharide, they are
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gram-negative
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The prokaryotic genome is contained in the
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nucleoid region.
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Archaebacteria and bacteria do not differ in their
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presence in nonextreme environments.
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Genetic recombination has led to antibiotic resistance through the transfer of
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plasmids.
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Prokaryotic organisms that obtain their energy by oxidizing inorganic substances are called
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chemoautotrophs.
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What disease is experiencing new outbreaks because of antibiotic resistance?
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tuberculosis
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The disease sometimes referred to as the "silent STD" because it is usually asymptomatic in women early on is
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chlamydia
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What tasks can be attributed to bacteria?
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decomposition of dead organic matter, increasing oxygen levels in the atmosphere, and production of antibiotics
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An atom gains energy when
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it undergoes reduction.
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Which of the following is concerned with the amount of energy in the universe?
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the First Law of Thermodynamics
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In a chemical reaction, if ΔG is negative, it means that
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the reaction will proceed spontaneously.
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A catalyst does what?
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lowers the amount of energy needed for a reaction to proceed.
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Do all the cells of an organism contain the same enzymes?
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No, this is false.
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A multienzyme complex contains
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enzymes that catalyze a series of reactions.
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What are factors that can have an effect on the rate of enzyme-catalyzed reactions?
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temperature, ph, and concentration of substrate
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How is ATP used in the cell to produce cellular energy?
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ATP hydrolysis is coupled to endergonic reactions.
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Anabolic reactions are reactions that
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make chemical bonds.
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How is a biochemical pathway regulated?
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The end product inhibits the first enzyme in the pathway by binding to an allosteric site.
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