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Biology Study Guide
Chapter 1: Scientific Method
-Inductive reasoning draws a generalization from several specific observations, specific--
>general...impossible to prove the generalization. Inductive is best for arguments based on
experience or observation
-Deductive reasoning gathers all of the information at hand and draws conclusions from the
observations. Deductive is best for observations based on laws, rules, or other widely accepted
principles.
-Scientific Method: Observation>hypothesis>experiment>result>conclusion
Chapter 2: Atoms
-Radioisotopes-have an unstable nucleus, atomic nuclei undergoes decay...decay is a statistical
average used to measure the passage of time (isotopes have different # of neutrons)
-Molecule- 2 or more atoms held together by a covalent bond
-Compound- 2 or more different elements held together in a fixed ratio by any type of bond
Chapter 3: Water
-Water has high specific heat, high heat of vaporization (evaporative cooling is another
mentioned...where when water evaporates the warmest are converted to vapor and a cool liquid
is left), polarity, versatility as a solvent, expands upon freezing (because of the orderly
placement of hydrogen bonds in the solid form)
-Water molecules form up to 4 hydrogen bonds
-Cohesion- attraction between molecules of the same substance (responsible for surface
tension) vs adhesion...attraction between molecules of a different substance
-Buffers minimize pH changes by donating H+ ions when bases are added and accepting H+
ions when acids are added...blood has a buffering system
-The pH of most living cells is usually around 7.2 or 7.4
-The pH scale calculations are log scale – by 10. (10, 100, 1000…)
Chapter 4: Organic Chemistry Stuff
-Organic compounds= (carbon skeleton+hydrogen/functional groups)
-CO2, and all molecules without carbon are inorganic
-Isomers- same molecular formula, different structures: 2 types: structural = different
arrangement of covalent bonds; stereoisomers= same arrangement of covalent bonds, but the
spacial arrangement is different.
-Stereoisomers (2 types important): cis-trans isomers are associated with C=C (double bond
carbons) where the larger items are either on the same side (cis) or opposite side (trans) of
carbons. Enantiomers are substances that are mirror images...sometimes called optical
isomers, only one is useful for organisms
-Major classes of organic compounds- carbohydrates, lipids, proteins (also called polypeptides),
and nucleic acids...get their properties from functional groups.
Functional Groups: (- are bonds, = are double bonds X is the rest of the molecule)
-Hydroxyl is polar, and found in alcohols X-OH
-Carbonyl is polar, and found in aldehydes and keytones X-C=O
-Carboxyl is weakly acidic and found in organic acids (amino acids) X-COOH
-Amino is weakly basic, found in amino acids X-NH2
-Sulfhydryl is non-polar and found in some amino acids X-SH
-Phosphate is weakly acidic and found in phospholipids X-PO4H2
-Methyl is non-polar and found in lipids and other membrane X-CH3
-Carboxyl and amino are always in amino acids
Chapter 5: Biological Molecules
(Very long section, also a very important section!)
Dehydration Synthesis- monomers are covalently linked to form polymers by removing a water
molecule
Hydrolysis- polymers are degraded back into monomers through the addition of a water
molecule
-The major classes of biological molecules are carbohydrates, lipids, proteins (also called
polypeptides) and nucleic acids
-carbohydrates include sugars, starches, and cellulose
-carbohydrates contain only the elements carbon, hydrogen, and oxygen
-the ratio works out so that carbohydrates are typically (CH2O)n
-Functions: energy storage and structural construction
-Most small carbohydrates are water soluble.
-grouped into monosaccharides, disaccharides, and polysaccharides
-monosaccharides are simple sugars (a single monomer)
The ring form of sugar is predominate in solution
Glucose (grape sugar)--(C6H12O6)
--Functional groups: –OH and –H
--Usually found in a ring form in cells
--Diabetes: glucose level
Fructose (fruit sugar; found in corn syrup and fruits)
Galactose (milk sugar; found in lactose)
Ribose and deoxyribose (found in RNA and DNA)
disaccharides consist of two monosaccharide units, double sugars
the two monomers are joined by a glycosidic linkage during dehydration reaction.
Typically, the linkage is between carbon 1 of one and 4 of the other
maltose, sucrose, and lactose are common disaccharides
maltose (malt sugar): has two glucose subunits
sucrose (table sugar): glucose + fructose
lactose (milk sugar): glucose + galactose
Uses: short-term energy storage
polysaccharides are macromolecules made of repeating monosaccharides units
linked together by glycosidic bonds
number of subunits varies, typically thousands
can be branched or unbranched
some are for energy storage (examples: starch, glycogen); some are for
structural components (example: cellulose)
Starch (polymer of glucose)
Energy-storage molecules for plant
Formed in roots and seeds
glycogen (polymer of glucose)
main storage carbohydrate of animals
similar to starch, but very highly branched and more water-soluble
is NOT stored in an organelle; mostly found in liver and muscle cells
Cellulose (polymer of glucose)
Found in the cell walls of plants
Indigestible for most animals due to orientation of bonds between glucoses
fibrous cellulose is the “fiber” in your diet
some fungi, bacteria, and protozoa make enzymes that can break down
cellulose
animals that live on materials rich in cellulose, e.g. cattle, sheep and termites,
contain microorganisms in their gut that are able to break down cellulose
for use by the animal
Chitin (polymer of modified glucose units)
insects, crabs, and spiders
cell walls of many fungi
lipids are fats and fat-like substances
The one class of large biological molecules that do not form polymers
Characteristics
---C, H, O
---Long chains of nonpolar hydrocarbons
---Hydrophobic
Types
---Oils, fats and waxes
---Phospholipids
---Steroids
Oil, fats (triacylglycerols) and waxes -- contain glycerol joined to three fatty acids
glycerol is a three carbon alcohol with 3 -OH groups
a fatty acid is a long, unbranched hydrocarbon chain carboxyl group at one end
saturated fatty acids contain no carbon-carbon double bonds (usually solid at
room temp)
unsaturated fatty acids contain one or more double bonds (usually liquid at room
temp)
monounsaturated – one double bond
polyunsaturated – more than one double bond
condensation results in an ester linkage between a fatty acid and the glycerol
triacylglycerols (also called triglycerides) are the most abundant lipids, and are
important sources of energy
Waxes
--Long hydrocarbon chains
--Hydrophobic
--Highly saturated and solid
--Waterproofing
phospholipids
2 fatty acids and a phosphate group attach to glycerol
Fatty acid tails are hydrophobic, but phosphate heads are hydrophilic.
Form plasma membranes -- phospholipid bilayer
--Interior: hydrophobic;
--Outside: hydrophilic.
Steroids
Lipids characterized by a carbon skeleton consisting of four fused rings
Side chains are different.
Cholesterol is an important steroid, is a component in animal cell membranes
other examples: many hormones such as testosterone, estrogens
proteins are macromolecules that are polymers formed from amino acids
monomers linked together by peptide bonds
---Polymer: polypeptide
---Monomer: amino acid
---By peptide bonds
proteins have great structural diversity and perform many roles
roles: diversity [include enzyme catalysis, defense, transport, structure/support,
motion, regulation; protein structure determines protein function]
Protein structure determines its function.
Amino acids consist of a central or alpha carbon; bound to that carbon is a
hydrogen atom, an amino group(-NH2), a carboxyl group (-COOH), and a variable
side group (R group)
the R group determines the identity and much of the chemical properties of the
amino acid
there are 20 amino acids that commonly occur in proteins; pay attention to what
makes an R group polar, nonpolar, or ionic (charged) and thus their
hydrophobic or hydrophilic nature
the peptide bond joins the carboxyl group of one amino acid to the amino group
of another; is formed by a condensation reaction
the sequence of amino acids determine the structure and the properties of a protein
proteins have 4 levels of organization or structure
primary structure (1°) : amino acid chain linked by peptide bonds.
secondary structure (2°) : coiled α-helix or folded β-pleated sheet, resulting from
hydrogen bonds.
tertiary structure (3°): overall folded shape of a single polypeptide chain,
determined by secondary structure combined with interactions between R groups:
--hydrogen bonds
-- ionic bonds
-- hydrophobic interactions
-- disulfide bridges
quaternary structure (4°): interactions between two or more separate
polypeptide chains, stabilized by hydrophobic interaction force.
when present, 4° structure is the final three-dimensional structure of the protein
(the protein conformation)
example: hemoglobin has 4 polypeptide chains
not all proteins have 4° structure
protein conformation determines function
denaturation is unfolding of a protein, disrupting 2°, 3°, and 4° structure
Change in the environment (temperature, pH, or exposure to various chemicals)
can change the shape of a protein = denature the protein
denatured proteins typically cannot perform their normal biological function
denaturation is generally irreversible
Nucleic acids transmit hereditary information by determining what proteins a cell makes
Polymer: polynucleotides (nucleic acid chains).
Monomer: nucleotides
Nucleotide structure:
Phosphate group
Five-carbon sugar (DNA: deoxyribose; RNA: ribose)
Nitrogen-containing base (DNA: A, G, T, C --- RNA: A, G, U, C)
purines are double-ringed nitrogenous bases A, G
pyrimidines are single-ringed nitrogenous bases C, T (U)
Be able to draw a nucleotide structure. (See index)
Nucleotides are fastened together by phosphodiester bonds
the phosphate group of one nucleotide is fastened to the sugar of the adjacent
nucleotide--backbone (ribbon looking outsides)
the joining is yet another condensation reaction
the way that the are joined creates a polynucleotide strand with 5’ and 3’ ends
Two types of nucleic acids
DNA:
---Deoxyribonucleic acid.
---A,G,C and T.
---Double helix (hydrogen bonds stabilize).
---Build chromosomes to carry genetic information.
---Antiparallel: In the DNA double helix, the two backbones run in opposite 5’→
3’ directions from each other.
---Complementary base pairing role: A-T (forms 2 hydrogen bonds); G-C
(forms three hydrogen bonds)--G-C makes more stable structure because it forms
three hydrogen bonds
-Histone protein-stores genetic structure into chromosome
RNA:
---Ribonucleic acid.
---A, G, C, and U (U instead of T).
---Single strand.
---Copies from DNA, direct the synthesis of proteins
---Have a OH attached to the 2 carbon, instead of a single hydrogen (DNA)
---RNA is unstable because of the OH group and being attacked by many polar
molecules
Adenosine triphosphate (ATP) an important energy carrying compound
-three phosphate groups, links to the 5’ carbon of RNA and adenine, bonds between the three
phosphate group (2 high energy bonds) breakdown releases energy...ATP is energy carrying
molecule
DNA Diagram
Review Table
Molecules Polymer Monomer linkage categories properties function/o
ther
Carbohydra polysacch monosacc glycosidic mono- solubility know this
te aride haride linkage di- yes, yes, and
poly- no examples
understand
alpha and
beta
glucose
structure
Lipid some <----- ester fat, oil, water energy
times phospholipi insoluble storage,
glycerol + ds cell
fatty acid, membrane
some type component
are made , steroids,
by alcohol hormones
chain, etc no
most are others
hydrocarb
on units
Proteins polypeptid amino peptide diverse water 4 level
e acid bond or enzyme, soluble, structure
amino peptide transport some have (Primary,
group + linkage protein etc many Secondary,
carboxyl hydrophobi Tertiary,
group c groups Quaternary
sitting )
outside chaperonin
and are protein--
insoluble assists in
folding
other
proteins
protein
denaturing
Nucleic polynucle nucleotide phosphodie DNA, RNA, information DNA
acid otide ster bonds ATP or energy direction,
chain storing nucleotide
structure,
DNA
structure,
DNA RNA
difference
Chapter 6: Cells
-Robert Hooke discovered cells using a light microscope viewing tree cork cells; light
microscopes can usually differentiate between cells, but that’s about it.
-Electron Microscope types are: scanning electron microscope-used to study the surface of
specimen, and transmission electron microscope-studies the internal surface
-Cell Fractionation- used to separate cell parts based on density...homogenization,
centrifugation, collection at each speed.
Prokaryotic cells Eukaryotic cells
Archaea or Bacteria Everything else
Nucleoid Nucleus
Most unicellular Most are multicellular
Many don’t use Most use oxygen
oxygen
No memb bound Organelles
organelles
Singl, small, Many linear DNA
circular DNA
(plasmid)
-Know all about the different organelles:
-Nucleus-nuclear envelope is a double membrane, nucleolus is the site of rRNA synthesis
-Ribosomes-made up of rRNA and protein, used for protein synthesis, MRNA is in the middle
and it holds genetic material
-Rough ER-continuous with nuclear envelope, has ribosomes, secretes glycoproteins,
distributes transport vesicles
-Smooth ER-continuous with nuclear envelope, synthesizes lipids, detox of drugs and poisons
-Golgi Apparatus-cisternae are flattened sacs, cis face is the receiving side, trans face is the
shipping side.
-Lysosomes- budded from Golgi, contain digestive enzymes, low pH
-Vacuoles- food vacuoles bud from plasma membrane and fuse with lysosomes for digestion,
contractile vacuoles maintain water balance, central vacuoles are important in plants...maintain
water balance, storage of different things, maintain turgor pressure
-Mitochondria-inter-membrane space, cristae....are the foldings, matrix space=circular
mitochondrial DNA, site of ATP synthesis, and mitochondrial ribosomes
-Plastids- Amyloplasts store starch, chromoplasts color petals and fruits, chloroplasts--stroma
space (inner membrane space, contains the thylakoids which are stacked into granum)
-Endosymbiont Theory-mitochondria and chloroplasts both have their own circular DNA and
ribosomes and double membranes, so it is thought that a psudeopod engulfed prokaryotic non-
photosynthetic prokaryotes and then photosynthetic prokaryotes
-Peroxisomes-oxidation, produce H2O2 to break down things and then convert them to water,
glyoxysomes-found in fat storage tissues of plant seeds...another specialized digestive
organelle
-Cytoskeleton-.for structure and cellular support and transport of materials. Motor proteins:
Protein Complexity Work with Function
Myosin less muscle fiber muscle
contraction
Dynein more microtubule cause cilia and
flagella
movement
Kinesin more microtubule cargo transport
and cell
division,
regulate
spindle fiber
-Also cilia and flagella, different junctions and etc that goes along with cytoskeleton
-Protein secretion process-ribosome>rough ER (folding)>vesicles>
Chapter 7: Cell Membrane
-amphipathic-hydrophyllic phosphate heads and hydrophobic fatty acid tails
-homeoviscous adaptation- increase in saturated fatty acids at higher temperatures (makes
membrane more fluid) and increase in unsaturated fatty acids at lower temperatures (makes
membrane more solid)
-Cholesterol-functions in animal membranes to stabilize the membrane...makes it stronger and
more flexible, less permeable to water-soluble substances, less of the homeoviscous non-
sense.
-Peripheral proteins are on the surface and integral proteins are embedded.
-Know about osmosis, diffusion and etc...hypotonic, hypertonic...
-Facilitated diffusion is through a channel/carrier protein, but no energy is needed so it is
passive transport...aquaporins are water channels
-Active transport moves things against concentration gradient using ATP, example. Na/K pump
-Endocytosis- (moves materials into the cell) pinocytosis “cell drinking” brings in smaller
materials, receptor mediated endocytosis eats specific molecules, phagocytosis “cell eating”
moves large particles or even whole cells: psudeopods make a vacuole that extends out and
then fuses with lysosomes (amoeba) white blood cells can also do this to eat
bacteria...exocytosis moves materials outside the cell
-Cell junctions: desmosomes are found in animal cells, anchor cells together for cell support.
Tight junctions are leakproof and form on the outside of plasma membranes...support. Gap
junctions form a channel between two animal cells, Plasmodesmata are bridges between plant
cells...the plant equivalent of gap junctions.
Chapter 8: Metabolism
-Body weight represents balance between all the energy you get and all the energy you use
-Laws of Thermodynamics: 1. Energy is not created or destroyed, it only changes forms. 2. All
energy transformations are inefficient, most energy is converted into heat and released into the
surroundings, and that increases entropy (disorder). Entropy is the measure of energy not
available for us to use. Living organisms use solar energy to create the low entropy conditions
of life
-Metabolism-sum of all chemical reactions in an organism; Catabolic pathways release energy
(Complex--->Simple) an example is cellular respiration, involves decomposition reactions.
Anabolic pathways consume energy, (Simple--->Complex) an example is photosynthesis.
-Coupled reactions involve both endergonic (energy absorbing) and exergonic reactions (energy
releasing) energy carrying molecules are examples of coupled reactions but they must have a
net exergonic nature to count.
-Free energy: (DeltaG=G final - G initial) is the energy available to do work in a chemical
reaction. This can be positive or negative. In exergonic it is negative and in endergonic it is
positive. -Delta G are spontaneous reactions, more free energy=less stable=more capacity to do
work.
-ATP=nucleotide with adenine base, ribose sugar and a chain of three phosphate groups. The
two phosphate bonds are unstable and release high energy during hydrolysis.
-Phosphorylated Intermediaries- ATP hydrolysis is coupled to a reaction to provide energy. The
Pi (inorganic phosphate) that breaks off is transferred to another compound rather than
immediately released...in a higher energy state.
-Electron carriers can transfer high energy electrons in glucose metabolism and photosynthesis
(NAD+ and FAD are two common ones)
-Enzymes can be inhibited in competitive inhibition (another substrate binds to active site) or
noncompetitive inhibition (binds to another part of the molecule and changes the shape of the
enzyme so that the substrate can’t bind to it)
-Cofactors-nonprotein enzyme helpers that can be inorganic or organic. Coenzymes are organic
cofactors.
Chapter 9: Cellular Respiration
-3 types: aerobic respiration, anaerobic respiration and fermentation
-Aerobic respiration is a redox reaction, the reactions it involves include:
-Substrate level phosphorylation-coupled reactions that happen in glycolysis and the krebs
cycle...an inorganic phosphate is removed from an intermediate high energy substrate and goes
directly to ATP or GDP to produce ATP or G3P(glycerol)
-Oxidative Phosphorylation- involves the electron transport chain and the synthesis of most of
the ATP at the end of cellular respiration...explained in more detail below...just wanted to add it
here to make a clear distinction
-Dehydrogenation Reactions-redox reactions that transfer hydrogen to NAD+ or FAD
-Decarboxylation reactions-carboxyl groups are removed, CO2 is released
-Preparation Reactions-molecules are rearranged to prepare for other reactions
-Only substrate level phosphorylation and dehydrogenation provide energy for cells
-Coenzymes-NAD and FAD accept electrons and hydrogens to become NADH and FADH and
deliver electrons and hydrogens to ETP
-Aerobic Respiration has 4 stages: 1. Glycolysis 2. Pyruvate oxidation (forms acetyl-CoA) 3. The
Krebs Cycle 4. Oxidative Phosphorylation (Electron Transport Chain)
-Glycolysis- 1 glucose is broken down into 2 pyruvate molecules in the cystol, this does not
require oxygen. 2 net ATP’s per glucose molecule. NAD’s are converted to NADH’s. It
consumes 2 ATP’s and produces 3 G3P’s during the energy investment phase and produces 4
ATP’s, 2 pyruvates and 2NADH during the energy payoff phase.
-Pyruvate Oxidation- NAD is reduced to NADH and Pyruvate is changed into Acetyl CoA and
CO2.
-The Krebs Cycle- This is also called the tricarboxylic acid cycle, TCA cycle and citric acid
cycle. Net production = 2 molecules of ATP, Acetyl CoA-->CO2, NAD is reduced to NADH and
FAD is reduced to FADH2. Glucose has been completely catabolized, yet only 4 ATP have
been formed...rest of energy has been stored in NADH and FADH2.
-Oxidative Phosphorylation, ETP and chemiosmosis: Electron transport chain is in the
cristae, NADH and FADH2 are oxidized in the electron transport chain. The ETC pumps
hydrogen ions across inner membrane space. ATP synthesis happens when H+ are pushed
through the ATP synthase channel protein. The final electron acceptor is O2 from water. 32-34
ATP’s are produced.
Glycolysis 2 ATP
Citric Acid Cycle 2 ATP
FADH2 oxidation (2 x 2) 4 ATP
NADH oxidation (8 x 3, 2 x 2 or 3) 28-30 ATP
TOTAL 36-38 ATP
-Anerobic respiration has an electron transport chain and uses other compounds as the final
electron acceptor (rather than O2), it produces ATP but much less than aerobic respiration.
Happens in bacteria cells.
-Fermentation- does glycolysis and fermentation in the cystol, fermentation produces either
ethanol (alcohol fermentation) or lactic acid (lactic acid fermentation). The only ATP this
produces comes from glycolysis (2 ATP), during fermentation, NADH is oxidized and
regenerated into NAD+.
Chapter 10: Photosynthesis
-Photosynthesis Reaction (A redox reaction like cellular respiration): 12H2O + 6CO2 + light
energy --> 6O2 + C6H12O6 + H2O
*The C for glucose comes from CO2, The H and O for glucose comes from H2O, the O in O2
and H2O comes from CO2, the H for H20 comes from initial H2O
-Stomata are pores in the leaf that let in CO2 and let out O2 and H2O, while stroma is the fluid
that surrounds the thylakoids within the chloroplasts where light independent reactions occur.
-Light Reactions occur in the thylakoid membrane, dark reactions (light independent or Calvin
cycle) occur in the stroma
Illustration of light reactions
Summary: Light energy is converted into NADPH and ATP, water is split by photosystem 2 so
that the hydrogen ions may be used for the electron transport, but as a byproduct, O2 is
produced...the basis of aerobic life. The final electron acceptor is NAD+
-Water splitting: H20-->1/2O2 + 2H+ + 2e-
-The ATP and NADPH formed here move on to the calvin cycle
Illustration of the Calvin Cycle (C3 Cycle):
*The ATP and NADPH from the Light reactions are used directly in the calvin cycle
Summary of the Calvin Cycle’s 3 phases:
1. Carbon Fixation: 6 CO2 combine with RuBP, a 5 carbon sugar. This reaction is catalyzed by
Rubisco, which is said to be the most abundant enzyme on Earth (fun fact!)
2. Carbon Reduction: The resulting 6 carbon molecule breaks down into 2 3 carbon molecules
of phosphoglycerate (PGA). These molecules are further phosphorylated by ATP and
NADPH to form G3P.
3. RuBP Regeneration: 12 G3P are formed. Two of these are used to synthesize glucose and
the other 10 are converted into 6 RuBP molecules and the cycle starts over.
*Note: It takes 6 CO2 to synthesize 1 glucose
-Electron Flow: Linear electron flow involves the primary pathway using both photosystems
and produces ATP and NADPH. Cyclic Electron Flow is seen in purple sulfur bacteria and
uses only PS1 and produces ATP but not NADPH, no O2 is released.
-Photorespiration- low CO2 and high O2, stomata close. Instead of CO2, Rubisco adds O2 to
RuBP in the Calvin Cycle and the cell releases CO2 as a product, no ATP or sugar is produced.
-C4 Plants- (light is abundant but water is scarce) have chloroplasts in mesophyll and bundle
sheath, while C3 plants have chloroplasts in only mesophyll. They reduce photorespiration. Two
stage carbon fixation-in the mesophyll cells, PEP carboxylase (primary enzyme instead of
rubisco) is used in place of PGA, 4 carbon molecules are transported to bundle sheath cells and
they drop them or release them to C3 cycle. Basically, mesophyll performs ONLY light reactions
and bundle sheath performs ONLY C3...example of C4=sugar cane, corn, crabgrass
-CAM Plants- open stomata at night and CO2 is fixed into organic acids, close stomata during
the day and CO2 is released for the calvin cycle...examples include desert plants
-C4 plants work by altering location of CO2 fixation and CAM plants work by altering timing...all
plants still use C3 cycle.
Chapter 12-13: Meiosis and Mitosis
-Cell cycle includes Growth, Synthesis and Phases of Mitosis= Prophase, Metaphase,
Anaphase and Telophase or PMAT
-G1 is the phase right after mitosis for recovery and normal growth, S or Synthesis phase is for
DNA synthesis to form sister chromatids, G2 is when the cell prepares to divide; the
chromosomes condense and the centromeres replicate, after that comes mitosis.
Phases in detail:
1. Prophase- chromosomes condense, mitotic spindle forms, nuclear envelope dissolves and
chromosomes attach to spindle (each pole of the cell has a microtubule organizing center,
animals have centrioles that set up the mitotic spindle, plants do not; Aster= short
microtubules that extend from centrioles)
2. Metaphase- spindle microtubules align chromatids at the metaphase plate
3. Anaphase- removal of cohesion proteins causes centromeres to separate, sister chromatids
separate and cell elongates
4. Telophase- cells split, nuclear envelope forms, chromosomes uncoil etc. Also cytokinesis
which in plant cells occurs when golgi vesicles line up and fuse to split the cell apart (cell
plate) and in animal cells when microfilaments (actin) ring contracts and pulls the cell apart
(cleavage)
-Cyclin Dependent kinases regulate checkpoints in cell division at G1 phase, G2 phase and
mitosis...most cells enter G0 after the G1 checkpoint, which means they are not actively working
towards cell division
Meiosis Diagram
A. Synthesis
B. Prophase 1-synapsis occurs, which is where homologous chromosomes pair up and form
tetrads, crossing over also occurs, which is a source of genetic variation, spindle assembles
(2n diploid)
C. Metaphase 1-homologous chromosomes pair up randomly (2n diploid)
D. Anaphase 1- homologous chromosomes separate (1n haploid)
E. Telophase 1- spindle fibers disappear...all the same characteristics of telophase...interkinesis
occurs...which is the break between meiosis 1 and meiosis 2 (which has sister chromatids
and not homologous chromosomes) (We now have 2 1n haploid cells)
F. Prophase 2- spindle fibers reform and capture chromosomes
G. Metaphase 2-duplicated chromosomes line up
H. Anaphase 2- sister chromatids separate
I. Telophase 2- everything separates...nuclear envelopes reform...etc
J. We now have 4 1n haploid gametes which will fuse in fertilization to produce 1 2n zygote
-Genetic Variation in Meiosis- 1. Independent assortment of chromosomes in metaphase 1
when they randomly line up and assort...number of possible combinations is 2^n where n is the
number of homologous pairs...humans=23 so it’s 2^23 2. Crossing over in prophase 1 creates
new allele possibilities 3. Random fertilization, fusion of gametes from two individuals, so
multiply 2^23 by 2 to get possible combinations
Chapter 14-15: Genetics
-Mendel’s law of segregation-2 alleles separate to each other during meiosis randomly...genetic
linkages, that is genes on the same chromosome that tend to be inherited together can make
this untrue in many cases, though crossing over during prophase 1 can break linkages
-Incomplete dominance=red+white=pink, co-dominance= red+white=red and white patches
-Multiple Alleles- 2 alleles for a given trait
-Pleiotropy-alleles at single locus have effects on two or more traits ex. Albinism
-Epistasis- one gene influences the phenotype that a second gene usually controls, masking
effects of second gene...ex. albinism gene masks gene for brown hair and brown eyes
-Polygenic traits- traits affected by the interaction of 2 or more genes, ex. Human skin color
-Recessive X linked alleles are expressed more often in males than females
-Non-disjunction- incorrect separation of chromosomes or chromatids during meiotic
anaphases, polyploidy is complete extra sets (3n) and is fatal in humans and most
animals...aneuploidy is 1 extra or 1 less of a single chromosome (Trisomy 21 for example)
Chapter 16: DNA
-Griffith-DNA is required for genetic transformation of bacteria...pneumococcus in mice
-Hershey Chase- viruses inject DNA into bacteria and take them over
-Chargraff’s Rule-amounts of A=T and G=C
-Watson-Crick Model=2 strands of nucleotides, sugar-phosphate backbone, bases produce
inward, nucleotides are linked by a 3’ to 5’ phosphodiester linkage, antiparalell strands,
hydrogen bonds hold certain bases, double helix
DNA Replication Process
1. Origins of replication “replication bubble” bacteria has 1 and eukaryotes have several.
2. Replication fork--y shaped region where new DNA strands are growing at each end
3. DNA helicases- separate strands, single stranded DNA binding proteins keep it open
4. Topoisomerases break and rejoin the strands to stabilize the double helix
5. DNA polymerases synthesize new daughter strand, can only proceed in 3’-->5’ direction
6. Primase-starts new strand by making an RNA primer
7. Leading strand is continuous, lagging strand is formed by making small okazaki fragments
joined by DNA ligase
DNA Packaging
-Nucleosomes are subunits consisting of 8 histones with DNA thread
-Histones are positively charged and associated with negatively charged phosphates of DNA
-Histone H1 is associated with linker DNA regions
-Scaffolding proteins are non-histone proteins
Chapter 17: Protein Synthesis
-Central Dogma=DNA>RNA>Protein
-Types of RNA
Messenger RNA (mRNA): carries DNA information to the ribosome (codon)
Transfer RNA (tRNA): brings amino acids to the ribosome (anticodon)
Ribosomal RNA (rRNA): part of the structure of ribosomes
-Process of Protein Synthesis
1. Transcription occurs in the nucleus, mRNA forms from DNA template; Initiation is when
RNA polymerase binds to the promotor region (TATA box), start codon=ATG, 5’->3’
direction; Elongation-RNA polymerase adds free RNA nucleotides to elongate the strand,
RNA peels away, DNA winds back up; Termination-RNA polymerase reaches a
terminator (TAA) and releases completed mRNA strand.
2. Post-transcriptional modification-modify premRNA, 5’ cap consists of a modified guanine
residue, needed to bind to eukaryotic ribosomes. 3’ is poly A tail...a lot of adenines,
facilitates export of mRNA out of nucleus and makes less susceptible to degradation. RNA
splicing-Splicisomes (snRNP’s + snRNA’s) recognize intron sites and cut them out.
3. Translation- p site- peptidyl tRNA binding site, E site- exit site, A site-Aminoacyl tRNA
binding site 1. Initiation- initiation complex assembles with methionine (AUG) carried by
first tRNA, an anticodon in tRNA complementary pairs with codon in mRNA 2.
Elongation-Amino acids are added, translation proceeds along mRNA in 5’>3’ direction,
this has three steps. Codon recognition is when the second tRNA binds to A (growing)
site, peptide bond formation is when polypeptides are removed from p site and attached to
a site, amino end to carboxyl end, translocation is when the tRNA moves with the
polypeptide from A to P site, Empty tRNA goes to E site and releases, ribosomes move
down mRNA by 1 codon. 3. Termination-complex dissociates once it reaches the stop
codon
Diagram of Protein Synthesis
Mutations-changes in DNA sequence
-Point mutations are substitution; can be silent mutations which have no effect on amino acid
sequence, missense mutations (ex. sickle cell anemia), which code for incorrect amino acids or
nonsense mutations which change codon into a stop codon
-Insertions and deletions can cause frameshift mutations which change the reading frame and
amino acid sequence...mutated protein is almost always non-functional
-Inversions and translocations-split genes, not problematic if entire gene is moved
-Transposon-jumping DNA in prokaryotes and eukaryotes
-Neutral mutations, bad mutations and good mutations
-mutations are ultimate source of genetic variation
Chapter 20: Biotechnology
-Review this section in the book, not very long but they might ask questions on it
Chapter 22: Evolution
-Support for Evolution
1. Fossil Record
2. Comparative Morphology-Homologous features-similar structure due to common
evolutionary origin; Analogous features-similar in structure but not in function, no common
ancestry---convergent evolution; Vestigial Features-once had a role in evolutionary history
but no longer functions
3. Embryology
4. Molecular biology-DNA, 20 amino acids, ATP, some gene sequences are conserved across
organisms ex. cytochrome c
-Mutation is the ultimate source of genetic variation
Chapter 23 Evolution of a Population
-Hardy Weinberg Equilibrium
p2(frequency of homozygous dominant)+2pq(frequency of heterozygotes)+q2(frequency
of homozygous recessive)=1
-Hardy-weinberg equilibrium is only present if there are:
A. No mutations
B. No gene flow between populations
C. No genetic drift
D. non-random mating only
E. no natural selection
-Population bottleneck-change in allele frequency due to chance that occurs after a large
population reduction...ex. a flood leaves only 5 individuals alive when before there were
50...those five might have the same or different genotypes and that disrupts the allele
frequencies
-Founder Effect-small subpopulation migrates to a new area, allele frequencies can be
different
-Genetic Drift- causes allele frequencies to change at random
-3 types of natural selection
-Directional selection-one extreme phenotype is favored (ex. Tall in giraffes)
-Disruptive selection-either extreme is favored (ex. A bird population where there are
only large seeds and small seeds to eat, no intermediate sized seeds...so intermediate
size beak would not be selected for, large would mate with large and small would mate
with small)
-Stabilizing Selection- favors the average phenotypes of the population
-Note: Mutations can be good, bad or neutral (neutral is only point mutations that do not
effect the proteins)
Chapter 24: Species
-Biological species concept-separates species by degree of genetic exchange between their
gene pools (only works for sexual)
- Phylogenetic species concept-unique organisms with a unique genetic history (sexual or
asexual)
- Morphological species concept-defines a species by morphology
- Ecological species concept-defines species by ecological nitche
-Compare different concepts, understand the application and problems of each concept.
-What is reproductive isolation: prezygotic and postzygotic
-Describe the five isolation mechanisms to cause prezygotic barriers: 1. habitat isolation 2.
temporal isolation 3. behavioral isolation 4. mechanical isolation 5. gametic isolation--sperm
cannot fuse with egg
-Describe the three isolation mechanisms to cause postzygotic barriers: 1. hybrid inviability--
zygote forms from 2 species but develops abnormally 2. hybrid sterility 3. hybrid
breakdown...some first generation can reproduce, but any F2 can’t
-anagenic speciation-gradual change of 1 species to a new species
-cladogenic speciation- branching off from 1 species to new species from common
ancestor...branching evolution
-allopatric speciation- population is divided into geographically isolated areas...grand canyon
squirrels
-sympatric speciation- speciation takes place in geographically overlapping areas, mechanisms
include polyploidy, auto- same species, allo- 2 different species...common reason for sympatric
speciation in plants. Habitat differentiation-fish in colors of water and sexual selection, the fish
only mate with their color...disruptive selection-extreme phenotypes either way are favored,
directional selection- 1 extreme, stabilizing- heterozygotes
Chapter 52 & 54
-Know about the biosphere, biomes and etc.
-Camouflage-blending into environment
-Müllerian Mimicry- 2 or more harmful species who share common predators mimic each other’s
warning signs
-Batesian Mimicry- a harmless creature mimics a harmful one
-Warning coloration-bright colors, makes stand out... aposematic coloration is another name
-Startle coloration- color displayed by a prey organism suddenly when approached by predator
-know about interactions between species (parasitism, mutualism, etc)
