Hesi A2 Entrance Exam - Biology Section

Front 1

What is Biology?

Back 1

The study of life.

Front 2

Steps for scientific experiment

Back 2

Hypothesis - statement or explanation of certain events/happenings

Experiment - Repeatable procedure of gathering data to support or refute the hypothesis

Conclusion

Hint 2

3 steps

Front 3

Hierarchy system of organization

(Largest to smallest)

Back 3

Kingdom

Phylum

Class

Order

Family

Genus

Species

K,P,C,O,F,G,S

Hint 3

K,P,C,O,F,G,S

Front 4

Water

Back 4

-Makes life possible

-2 H atoms covalently bonded 1 O atom

-Polar nature allows H bonding between molecules

Front 5

Water Attributes

Back 5

High specific heat (amount of heat needed to raise temp of one molecule by 1 C) - allows water to resist shifts in temperature.

Versatile solvent - polarity of water allows it to be used to dissolve many substances

Front 6

Hydrogen Bonding

Back 6

Cohesion - the ability of a molecule to stay bonded or attracted to another molecule of the same. (Ex: water runs together on waxed car)

Adhesion - the ability of water to bond or attract other molecules or substances (Ex: Water sprayed on wall and some sticks to wall)

Front 7

Lattice

Back 7

-when water freezes

-causes the molecules to spread apart resulting in floating

Front 8

Biologic Molecules

Back 8

-Carbohydrates

-Lipids

-Proteins

-Nucleic Acids

Front 9

Carbohydrates

Back 9

-Long chains (polymers) of sugar

-Functions: storage, structure, energy.

Front 10

Lipids

Back 10

-Fatty acids

-Phospholipids

-Steroids

Front 11

Fatty Acids

Back 11

-Saturated fats

-Unsaturated Fats

Front 12

Saturated Fats

Back 12

-Contain no double bonds in hydrocarbon tail

-Solid at room temperature

-Can lead to cardiovascular problems with diets high in sat. fats

Front 13

Unsaturated Fats

Back 13

-Contain double bond in hydrocarbon tail

-Liquid at room temperature

Front 14

Phospholipids

Back 14

-2 fatty acids varying in length bonded to phosphate group

-Phosphate group is charged and polar

-Hydrocarbon tail of fatty acids non polar.

-Important function of cellular membranes =

creates a barrier that protects cells

Front 15

Steroids

Back 15

-Component of membranes

-Many precursors to significant hormones

Front 16

Proteins

Back 16

-Most significant contributor to cellular function

-Polymers of 20 molecules called amino acids

-Largest of biologic molecules

Front 17

Enzymes

Back 17

-Types of proteins that catalyze different reactions or processes

-Cellular function is catalyzed by some type of enzyme

Front 18

Nucleic Acids

Back 18

-Components of molecules of inheritance

-DNA and RNA

Front 19

Deoxyribronucleic Acid (DNA)

Back 19

Unique molecule specific to a particular organism and contains code necessary for replication

Front 20

Ribonucleic Acid (RNA)

Back 20

Used in transfer and as a messenger in most species of genetic code

Front 21

Metabolism

Back 21

-The sum of all chemical reactions that occur in an organism

-All reactions are catalyzed by enzymes

Front 22

Metabolic pathways

Back 22

In a cell, reactions take place in a series of steps progressing from high energy to low energy

Front 23

The Cell

Back 23

-Fundamental unit of biology

-Consist of many components (organelles)

Front 24

Types of Cells

Back 24

-Prokaryotic

-Eukaryotic

Front 25

Prokaryotic cells

Back 25

-No defined nucleus

-Does not contain membrane bound organelles

Front 26

Eukaryotic cells

Back 26

-Has membrane enclosed nucleus

-Has membrane bound organelles that carry out functions as directed by nucleus

-The more complex cell

Front 27

Nucleus

Back 27

-Contains DNA of the cell in organized masses called chromosomes

Front 28

Chromosomes

Back 28

-Contain all material for regeneration of cell, and instructions for the function of organelles

-Every organism has characteristic # of chromosomes specific to that particular species

Front 29

Ribosomes

Back 29

-Read RNA produced in the nucleus & translate genetic instructions to produce proteins

-Cells w/ high rate of protein synthesis have a large # of ribosomes

-Found attached to endoplasmic recticulum and free in cytoplasm

Front 30

Endoplasmic Recticulum (ER)

Back 30

-Attached to nuclear membrane and has two parts: rough ER and smooth ER

Front 31

Rough ER

Back 31

-Covered w/ ribosomes

-Responsible for protein synthesis and membrane production

Front 32

Smooth ER

Back 32

-Functions as detoxification and metabolism of multiple molecules

Front 33

Golgi Apparatus

Back 33

-Packaging, processing, and shipping organelle

-Transports materials from ER throughout cell

Front 34

Lysosomes

Back 34

-Where intracellular digestion takes place

-Packed w/ hydrolytic enzymes(can hydrolyze proteins, fats, sugars, and nucleic acids)

Front 35

Vacuoles

Back 35

-Membrane-enclosed

-Various functions depending on type of cell

-Phagocytosis - uptake of food through cell membrane, creating a food vacuole

-Plant cells have a central vacuole - storage, waste disposal, protection, & hydrolysis

Front 36

Mitochondria & Chloroplasts

Back 36

-Both produce energy

-Mitochondria - found in most eukaryotic cells & site of cellular respiration

-Chloroplasts - found in plants & site of photosynthesis

Front 37

Cellular Membrane

Back 37

-Most important component of cell

-Protection, communication, passage of substance into & out of cell

-Bilayer of phopholipids w/ proteins (cholesterol and glycoproteins throughout)

-Phospholipids=amphipathic - bilayer creates a hydrophobic region between 2 layers of lipids - making it selectively permeable

-Proteins that pass completely act as highways for molecules into & out of cell

Front 38

Cellular Respiration

Back 38

-2 catabolic pathways

-Anaerobic counterpart: Fermentation

-C6 H12 O6 + 6O2 -->6CO2+6H2O

-Process in 3 steps: Glycolysis, Krebs cycle, and Electron transport chain

Front 39

Adenosine triphosphate (ATP)

Back 39

Adenosine triphosphate (ATP) used as currency of the cell

Front 40

Nicotinomide adenine dinucleoide (NADH)

Back 40

-Another compound that acts as a reducing agent and is a vehicle of stored energy

-Used as a precursor to produce greater amount of ATP in final steps of respiration

Front 41

Glycolysis

Back 41

-Step 1 of Cellular respiration

-Conversion of glucose to pyruvate

-Takes place in cytosol of cell

-Produces 2 ATP, 2 pyruvate, and 2 NADH

Front 42

Krebs Cycle

Back 42

-Step 2 of cellular respiration

-Pyruvate transported into mitochondria - used in first reactions (Krebs Cycle)

-Takes place in matrix of mitochondria

-For 1 glucose consumed, 2 ATP, 6 carbon dioxide, and 6 NADH are produced

Front 43

Electron Transport Chain

Back 43

-Step 3 of cellular respiration

-Oxidation of NADH to produce oxygen and water - Electron transport chain

-For every glucose molecule, 28 to 32 ATP can be produced.

-Conversion results in 32 to 36 ATP for every 1 glucose consumed

Front 44

Photosynthesis

Back 44

-Began w/ 1 glucose & resulted in a large production of energy in the form of ATP

-A precursor to glucose is produced in photosynthesis.

-6CO2+6H2O+Light Energy-->C6 H12 O6+6O2

-Reverse of cellular respiration

-Glucose used to produce energy but energy needed to produce glucose

-2 stages in photosynthesis: light reactions & Calvin cycle

Front 45

Light Reactions

Back 45

-Step 1 of photosynthesis

-Converts solar energy to chemical energy

-Cell produces ATP by absorbing light and using energy to split water molecule & transfer electron, creating Nicotinamide Adenine Dinucleotide Phosphate (NADPH) & producing ATP.

-Molecules used in Calvin cycle to produce sugar

Front 46

Calvin Cycle

Back 46

-Step 2 of photosynthesis

-Molecules from light reactions used to produce sugar

-The sugar produced is polymerized & stored as a polymer of glucose.

-Sugars are consumed by organisms or by plant itself to produce energy by cellular respiration

Front 47

Cell reproduction

Back 47

-Cells reproduce in 3 different processes.

-Fall into two categories: asexual and sexual reproduction

Front 48

Asexual reproduction

Back 48

-Two types:

-Binary fission

-Mitosis

Front 49

Binary Fission

Back 49

-Bacterial cells

-Chromosome binds to plasma membrane, where it replicates

-As cell grows, it pinches I two produced two identical cells

Front 50

Mitosis

Back 50

-Cell division in 5 stages before pinching in two forming two identical cells in process called cytokinesis

-5 stages are prophase, prometaphase, metaphase. anaphase, & telophase

Front 51

Prophase

Back 51

-Stage 1 of mitosis

-Chromosomes visibly separate

-Each duplicated chromosome has 2 chromatids

Front 52

Prometaphase

Back 52

-Stage 2 of mitosis

-Nuclear envelope begins to disappear

-Chromosomes begin to attach to the spindle that's forming along axis of cell

Front 53

Metaphase

Back 53

-Stage 3 of mitosis

-All chromosomes align along metaphase plate (center of cell)

Front 54

Anaphase

Back 54

-Stage 4 of mitosis

-Chromosomes start to separate

-Chromatids considered separate chromosomes

Front 55

Telophase

Back 55

-Stage 5 of mitosis

-Chromosomes gather on either side of now separating cell.

-End of mitosis

Front 56

Sexual Reproduction

Back 56

-Different from asexual reproduction (in asexual, offspring originates from single cells, all cells produced identical)

-2 cells contribute genetic material to daughter cells, resulting in greater variation

-2 cells find and fertilize each other randomly, making it virtually impossible for cells to be alike.

-Meiosis

Front 57

Meiosis

Back 57

-Process that determines how reproductive cells divide in sexually reproducing organisms.

-Before meiosis, period called interphase takes place (where chromosomes are duplicated & cell prepare for division)

-2 distinct stages: meiosis one and meiosis two, resulting in 4 daughter cells (each contains half as many chromosomes as the parent)

Front 58

Mitosis vs. Meiosis

Back 58

-First stage of meiosis - consists of 4 phases: prophase I, metaphase I, anaphase I, & telophase I and cytokinesis.

-Significant difference in prophase I.

-Nonsister chromatids of homologous chromosomes cross at numerous locations.

-Small section of DNA transferred between chromosomes - increased genetic variation

-Remaining 3 phases same as mitosis, with exception chromosomes pairs separate.

-After first cytokinesis, meiosis two begins (all 4 stages identical to mitosis)

-Resulting in 4 cells - half as many chromosomes as parent cell.

Front 59

Genetics

Back 59

-Gregor Mendel discovered basic principles of genetics by using garden peas (observable traits in peas passed from 1 generation to next)

-From Mendel, found that for every trait expressed in sexually reproducing organism, at least 2 alternative version of gene (alleles)

-Simple traits - 1 of 2 types: dominant or recessive

Front 60

Dominant allele

Back 60

-If allele is dominant for trait, letter is capitalized

-If dominant allele is present, phenotype expressed will be dominant.

Front 61

Recessive Allele

Back 61

-If allele is recessive, letter is lowercased.

-Only way recessive trait will be expressed is if both alleles are recessive.

Front 62

Homozygous

Back 62

-If both alleles are of same type, homozygous for the trait

Front 63

Heterozygous

Back 63

-If alleles are different types, organism is heterozygous

Front 64

Punnet Square

Back 64

-Used to predict genotype (combination of alleles) and phenotype (traits that will be expressed) of offspring of sexual reproduction

-Alleles placed one per column for one gene and one per row for other gene

-Can be used to cross any # of different traits

-Probability of phenotypes will be determined

-Other methods of genetic expression: multiple alleles, pleiotrophy, epistasis, polygenic inheritance

Front 65

Pedigree

Back 65

-A family tree that traces occurrence of a certain trait through several generations

Front 66

DNA

Back 66

-Genetic material of a cell and is a vehicle for inhertiance

-1953, Watson and Crick- double helical structure that contains 4 nitrogenous bases: adenine, thymine, guanine, cytosine

-Each base form hydrogen bonds w/ another base on complementary strand - bases have specific bonding pattern (Adenine - thymine & guanine - cytosine)

-Because of bonding, strands can be replicated, producing identical strands of DNA

Front 67

DNA

Back 67

-During replication, strands are separated.

-W/ help from enzymes, new complementary strands are created to each of 2 original strands

-Produces 2 new double stranded segments of DNA identical to original

-Each gene along a strand of DNA is a template for protein synthesis (begins with transcription)

Front 68

Transcription

Back 68

-An RNA strand, complementary to original strand of DNA, is produced

-Piece of genetic material produced is called messenger RNA (mRNA)

-RNA strand has nitrogenous bases identical to those in DNA w/ exception of uracil, which is substituted for thymine

-mRNA functions as a messenger from the original DNA helix in nucleus to ribosomes in cytosol or on rough ER (then translation)

Front 69

Translation

Back 69

-Ribosomes acts as site of translation (mRNA slide through ribosome)

-Every group of 3 bases along stretch of RNA (codon) - each of these codes for specific amino acid

-Anticodon located on transfer RNA (tRNA), which carries specific amino acid - binds to ribosome when codon slides though ribosome

-Protein is polymer of amino acids, multiple tRNA binds in order and released by ribosome

Front 70

Translation/transcription

Back 70

-Each amino acid is binded together & released by preceding tRNA, creating elongated chain of amino acids

-Stop codon - when chain is ended

-Chain is released into cytoplasm, protein folds onto itself & forms complete conformation

-By dictating what is produced in translation and transcription, DNA in nucleus has control over everything taking place in cell.

-Proteins that are produced will perform all different cellular functions required for cell's survival