ap bio exam review “greatest hits” · 2018. 10. 2. · “greatest hits” ap bio exam review:...
TRANSCRIPT
4/14/2016
1
AP Bio Exam Review “Greatest Hits” AP Bio Exam Review:
Evolution
Darwin’s Theory of Natural Selection:
1. Populations produce more offspring than can possibly survive.
2. Individuals in a population vary extensively from each other, mostly due to inheritance.
3. Struggle to survive: individuals whose inherited characteristics best fit to environment leave more offspring than less fit.
4. Unequal ability of individuals to survive and reproduce leads to gradual change in pop, with favorable characteristics accumulating over generations.
• Populations evolve, not individuals.
• Fitness is determined by the environment.
In summary:
Natural Selection = differential success in reproduction
Product of natural selection = adaptations of populations to environment
Evidence for Evolution
1. Biogeography – Geographic distribution of a species
– Geographic, reproductive isolation
2. Fossil Record – transitional forms
3. Comparative Anatomy 1. Homologous structures
2. Vestigial structures
4. Embryonic Development
5. Molecular Biology – DNA, proteins
Hardy-Weinberg Theorem:
• Frequencies of alleles & genotypes in a population’s gene pool remain constant from generation to generation unless acted upon by agents other than sexual recombination (gene shuffling in meiosis)
• Equilibrium = allele and genotype frequencies remain constant
4/14/2016
2
Hardy-Weinberg Equilibrium
Allele Frequencies:
• Gene with 2 alleles : p, q
p = frequency of allele “A” in a population
q = frequency of allele “a” in a population
p + q = 1
Genotype Frequencies: • 3 genotypes (AA, Aa, aa)
p2 = AA 2pq = Aa q2 = aa
p2 + 2pq + q2 = 1
Conditions for Hardy-Weinberg Equilibrium:
1. Extremely large population size (no genetic drift).
2. No gene flow (isolation from other populations).
3. No mutations.
4. Random mating (no sexual selection).
5. No natural selection.
Genetic drift: a change in a population’s allele frequencies due to chance
A. Bottleneck Effect – genetic drift due to drastic reduction in population size
» Certain alleles may be over/under represented
B. Founder effect – few individuals become isolated from larger population certain alleles over/under represented
Directional Selection: eg. beak sizes of birds during wet/dry seasons in Galapagos
Diversifying Selection: eg. small beaks for small seeds; large beaks for large seeds
Stabilizing Selection: eg. average human birth weight
Biological Species Concept
• Species = population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
– Reproductively compatible
• Reproductive isolation = barriers that prevent members of 2 species from producing viable, fertile hybrids
Prezygotic barriers impede mating or hinder fertilization if mating does occur
Postzygotic barriers prevent a hybrid zygote from
developing into a viable, fertile adult
REDUCED HYBRID
VIABILITY
REDUCED HYBRID
FERTILITY HYBRID BREAKDOWN
HABITAT ISOLATION TEMPORAL ISOLATION BEHAVIORAL ISOLATION MECHANICAL ISOLATION GAMETIC ISOLATION
Reduced
hybrid
viability
Fertilization Viable,
fertile
offspring
Reduced
hybrid
fertility
Hybrid
breakdown
Mating
attempt
Gametic
isolation
Fertilization
Mechanical
isolation
Behavioral
isolation
Temporal
isolation
Habitat
isolation
Individuals of
different species
Types of Reproductive Barriers
4/14/2016
3
Convergent Evolution
• Independent development of similar features between 2 unrelated species • Similar environments • Analogous structures • Eg. wings on bees & wings on birds
• Cladogram: diagram of evolutionary relationship of organisms
– Shared characteristics due to common ancestry
– Uses parsimony – simplest explanation, fewest DNA base changes for tree (“keep it simple”)
Cladistics : a form of systematics
LE
25-
11b
Turtle Leopard
Hair
Amniotic egg
Four walking legs
Hinged jaws
Vertebral column
Salamander
Tuna
Lamprey
Lancelet (outgroup)
Cladogram
AP Bio Exam Review: Biochemistry & Cells
1. Polarity of H2O
• O- will bond with H+ on a different molecule of H2O = hydrogen bond
• H2O can form up to 4 bonds
H2O Property Chemical
Explanation Examples of
Benefits to Life
Cohesion •polar •H-bond •like-like
↑gravity plants, trees transpiration
Adhesion •H-bond •unlike-unlike
plants xylem bloodveins
Surface Tension •diff. in stretch •break surface •H-bond
bugswater
Specific Heat •Absorbs & retains E •H-bond
oceanmoderates temps protect marine life (under ice)
Evaporation •liquidgas •KE
Cooling Homeostasis
Universal Substance •Polarityionic •H-bond
Good dissolver solvent
Acids and Bases
Acid: adds H+ (protons); pH<7
Bases: removes protons, adds OH-; pH>7
Buffers = substances which minimize changes in concentration of H+ and OH- in a solution (weak acids and bases)
• Buffers keep blood at pH ~7.4
• Good buffer = bicarbonate
4/14/2016
4
Functional Groups
Functional Group Molecular Formula Names & Characteristics Draw an Example
Hydroxyl -OH Alcohols Ethanol
Carbonyl >CO Ketones (inside skeleton)
Aldehydes (at end) Acetone Propanol
Carboxyl -COOH Carboxylic acids (organic
acids) Acetic acid
Amino -NH2 Amines Glycine
Sulfhydryl -SH Thiols Ethanethiol
Phosphate -OPO32- / -OPO3H2 Organic phosphates Glycerol phosphate
Dehydration Synthesis (Condensation Reaction)
Hydrolysis
Make polymers Breakdown polymers
Monomers Polymers Polymers Monomers
A + B AB AB A + B
+ H2O + + H2O +
I. Carbohydrates
• Fuel and building
• Sugars are the smallest carbs Provide fuel and carbon
• monosaccharide disaccharide polysaccharide
• Monosaccharides: simple sugars (ie. glucose)
• Polysaccharides: Storage (plants-starch, animals-glycogen)
Structure (plant-cellulose, arthropod-chitin)
Differ in position &
orientation of glycosidic
linkage
II. Lipids
A.Fats: store large amounts of energy
– saturated, unsaturated, polyunsaturated
B.Steroids: cholesterol and hormones
C.Phospholipids: cell membrane
– hydrophilic head, hydrophobic tail
– creates bilayer between cell and external environment
Hydrophilic head
Hydrophobic tail
amino acids polypeptides protein • Protein structure and function are sensitive to
chemical and physical conditions
• Unfolds or denatures if pH and temperature are not optimal
4/14/2016
5
IV. Nucleic Acids
Nucleic Acids = Information
Monomer: nucleotide
DNA RNA
•Double helix •Thymine •Carries genetic code •Longer/larger •Sugar = deoxyribose
•Single strand •Uracil •Messenger (copies), translator •tRNA, rRNA, mRNA, RNAi •Work to make protein •Sugar = ribose
AP Bio Exam Review: Cells and Membranes
Prokaryote Vs. Eukaryote • No nucleus
• DNA in a nucleoid
• Cytosol
• No organelles other than ribosomes
• Small size
• Primitive
• i.e. bacteria
• Has nucleus and nuclear membrane
• Cytosol
• Has organelles with specialized structure and function
• Much larger in size
• More complex
• i.e. plant/animal cell
• Cells must remain small to maintain a large surface area to volume ratio
• Large S.A. allows increased rates of chemical exchange between cell and environment
4/14/2016
6
Animal cells have intercellular junctions:
• Tight junction = prevent leakage
• Desomosome = anchor cells together
• Gap junction = allow passage of material
Cell Membrane 6 types of membrane proteins
hypotonic / isotonic / hypertonic
4/14/2016
7
Exocytosis and Endocytosis transport large molecules
3 Types of Endocytosis: • Phagocytosis (“cell eating” - solids)
• Pinocytosis (“cell drinking” - fluids)
• Receptor-mediated endocytosis
• Very specific • Substances bind to
receptors on cell surface
AP Bio Exam Review: Cell Energy
(Respiration & Photosynthesis)
Substrate Specificity of Enzymes
• The reactant that an enzyme acts on is called the enzyme’s substrate
• The enzyme binds to its substrate, forming an enzyme-substrate complex
• The active site is the region on the enzyme where the substrate binds
Allosteric Regulation
• a protein’s function at one site is affected by binding of a regulatory molecule at another site
• Allosteric regulation may either inhibit or stimulate an enzyme’s activity
Feedback Inhibition
• In feedback inhibition, the end product of a metabolic pathway shuts down the pathway
4/14/2016
8
Cellular Respiration Mitochondrion Structure
Citric Acid Cycle (matrix)
ETC (inner membrane)
Glycolysis
Fermentation
• Occurs in plants and animals
• Occurs in cytosol
• Keep glycolysis going by regenerating NAD+
• No oxygen needed
• Creates alcohol [+ CO2] or lactic acid
Respiration
• Release E from breakdown of food with O2
• Occurs in mitochondria
• O2 required (final electron acceptor)
• Produces CO2, H2O and up to 38 ATP (NADH, FADH2)
O2 present Without O2 Various sources of fuel
• Carbohydrates, fats and proteins can ALL be used as fuel for cellular respiration
• Monomers enter glycolysis or citric acid cycle at different points
Leaf cross section Vein
Mesophyll
Stomata CO2 O2
Mesophyll cell Chloroplast
5 µm
Outer membrane
Intermembrane space
Inner membrane
Thylakoid space
Thylakoid
Granum Stroma
1 µm
Sites of Photosynthesis
• mesophyll: chloroplasts mainly found in these cells of leaf
• stomata: pores in leaf (CO2 enter/O2 exits)
• chlorophyll: green pigment in thylakoid membranes of chloroplasts
Photosynthesis = Light Reactions + Calvin Cycle
“photo” “synthesis”
4/14/2016
9
Light Reactions
Both respiration and photosynthesis use chemiosmosis to generate ATP
Calvin Cycle = produce 3C sugar (G3P)
Photorespiration: low carbon-fixation when stomata closed in hot, dry climate
C3 C4 CAM C fixation & Calvin
together C fixation & Calvin in
different cells C fixation & Calvin at
different TIMES
Rubisco (normally fixes CO2)
PEP carboxylase fixes CO2
Organic acid
Mesophyll cells Mesophyll: fix CO2
Bundle Sheath: Calvin Cycle
Night: fix CO2 in 4C acids
Day: Calvin Cycle
Ex. rice, wheat, soybeans
Ex. sugarcane, grass Ex. cacti, pineapple,
succulent
AP Bio Exam Review: Genetics
4/14/2016
10
2nd division of
meiosis separates
sister chromatids
1st division of
meiosis separates
homologous pairs
Double division of meiosis
DNA replication
Meiosis 1
Meiosis 2
Mitosis vs. Meiosis
Trading pieces of DNA
• Crossing over – during Prophase 1, sister
chromatids intertwine
• homologous pairs swap pieces of chromosome – DNA breaks & re-attaches
tetrad
synapsis
prophase 1
What did Mendel’s findings mean?
• Traits come in alternative versions – purple vs. white flower color
– alleles • different alleles vary in the sequence of nucleotides
at the specific locus of a gene – some difference in sequence of A, T, C, G
purple-flower allele &
white-flower allele are two DNA
variations at flower-color locus
different versions of gene at
same location on homologous
chromosomes
What did Mendel’s findings mean?
• Some traits mask others
– purple & white flower colors are separate traits that do not blend
• purple x white ≠ light purple
• purple masked white
– dominant allele
• functional protein
– recessive allele
homologous
chromosomes
I’ll speak for both of us!
wild type
allele producing
functional protein
mutant
allele producing
malfunctioning
protein
Genotype vs. phenotype
• Difference between how an organism “looks” & its genetics – phenotype
• description of an organism’s trait
• the “physical”
– genotype • description of an organism’s genetic makeup
F1
P X
purple white
all purple
4/14/2016
11
Mendel’s 1st law of heredity
• Law of segregation
– during meiosis, alleles segregate
• homologous chromosomes separate
– each allele for a trait is packaged into a separate gamete
PP
P
P
pp
p
p
Pp
P
p
Mendel’s 2nd law of heredity • Law of independent assortment
– different loci (genes) separate into gametes independently • non-homologous chromosomes align independently
• classes of gametes produced in equal amounts
– YR = Yr = yR = yr
• only true for genes on separate chromosomes or on same chromosome but so far apart that crossing over happens frequently
round
wrinkled
yellow
green
: 1 1 : 1 : 1
Yr Yr yR yR YR YR yr yr
YyRr
Incomplete dominance
true-breeding red flowers
true-breeding white flowers
X P
100%
100% pink flowers
F1 generation (hybrids)
self-pollinate
��25% white
F2 generation
25% red 1:2:1
50% pink
Co-dominance
• 2 alleles affect the phenotype equally & separately
– not blended phenotype
– human ABO blood groups
– 3 alleles
• IA, IB, i
• IA & IB alleles are co-dominant – glycoprotein antigens on RBC
– IAIB = both antigens are produced
• i allele recessive to both
Polygenic inheritance
• Some phenotypes determined by additive effects of 2 or more genes on a single character
– phenotypes on a continuum
– human traits
• skin color
• height
• weight
• intelligence
• behaviors
Genes on sex chromosomes
• Y chromosome
– few genes other than SRY
• sex-determining region
• master regulator for maleness
• turns on genes for production of male hormones
– many effects = pleiotropy!
• X chromosome
– other genes/traits beyond sex determination
• mutations: – hemophilia
– Duchenne muscular dystrophy
– color-blindness
4/14/2016
12
Hemophilia
Hh x HH XHY XHXh
XHXh
XH
Xh
XHY
Y
XH
sex-linked recessive
XH Y male / sperm
XH
Xh
fem
ale
/ e
gg
s
XHXH
XHXh
XHY
XhY
XHXH XHY
XHXh XhY
carrier disease
Chromosomal abnormalities
• Incorrect number of chromosomes
– nondisjunction
• chromosomes don’t separate properly during meiosis
– breakage of chromosomes
• deletion
• duplication
• inversion
• translocation
Gene Mapping
If two genes are on the same chromosomes…
70
Now cross (AB ab) F1 progeny with (ab ab) tester to look for recombination on these chromosomes. Suppose you Get…… AB ab 583 parental
ab ab 597 parental
Ab ab 134 recombinant aB ab 134 recombinant total= 1448 268 recombinants /1448 progeny = 0.185 recombinants/progeny= 8.5% recombinants= 18.5 mu
Starting with pure breeding lines, Cross Parent 1(AA BB) with Parent 2(aa bb) Parental gametes in the F1 have to be AB and ab
Mapping the distance between two genes
AP Bio Exam Review: Molecular Biology
4/14/2016
13
Structure of DNA
Nitrogenous Bases
– Adenine (A)
– Guanine (G)
– Thymine (T)
– Cytosine (C)
• Pairing:
– purine + pyrimidine
– A = T
– G Ξ C
purine
pyrimidine
DNA Comparison
Prokaryotic DNA
• Double-stranded
• Circular
• One chromosome
• In cytoplasm
• No histones
• Supercoiled DNA
Eukaryotic DNA
• Double-stranded
• Linear
• Usually 1+ chromosomes
• In nucleus
• DNA wrapped around histones
(proteins)
• Forms chromatin
Flow of Genetic
Information in
Prokaryotes vs.
Eukaryotes
The Genetic Code
mRNA (5’ 3’) complementary to template
mRNA triplets (codons) code for amino acids in polypeptide chain
For each gene, one DNA strand is the template strand
Transcription Transcription unit: stretch of DNA that codes for a
polypeptide or RNA (eg. tRNA, rRNA)
RNA polymerase:
– Separates DNA strands and transcribes mRNA
– mRNA elongates in 5’ 3’ direction
– Uracil (U) replaces thymine (T) when pairing to
adenine (A)
– Attaches to promoter (start of gene) and stops at
terminator (end of gene)
4/14/2016
14
RNA Splicing
• Pre-mRNA has introns (noncoding sequences) and exons (codes for amino acids)
• Splicing = introns cut out, exons joined together
Translation
Most current definition for a gene: A region of DNA whose final product is either a polypeptide or an RNA molecule
A Summary of Protein Synthesis
Bacterial control of gene expression
Operon: cluster of related genes with on/off switch
Three Parts:
1. Promoter – where RNA polymerase attaches
2. Operator – “on/off”, controls access of RNA poly
3. Genes – code for related enzymes in a pathway
Repressible Operon (ON OFF)
4/14/2016
15
Eukaryotic gene expression
regulated at different stages
Gene Cloning
PCR (Polymerase Chain
Reaction): amplify (copy)
piece of DNA without use
of cells
Gel Electrophoresis: used to separate DNA molecules on
basis of size and charge using an electrical current (DNA
+ pole)
RFLPs – Disease Diagnosis
AP Bio Exam Review: Animal and Plant Systems
4/14/2016
16
Negative Feedback
• “More gets you less.”
• Return changing conditions back to set point
• Examples: – Temperature
– Blood glucose levels
– Blood pH
Plants: response to water limitations
Positive Feedback
• “More gets you more.”
• Response moves variable further away from set point
• Stimulus amplifies a response
• Examples: – Lactation in mammals
– Onset of labor in childbirth
Plants: ripening of fruit
Second Messengers • small, nonprotein molecules/ions that can relay
signal inside cell
– Eg. cyclic AMP (cAMP), calcium ions (Ca2+), inositol triphosphate (IP3)
Neuron = dendrite + cell body + axon
4/14/2016
17
Conduction of an action
potential
Cell communication: neurotransmitter released at synapses Axon (presynaptic cell) Dendrite (postsynaptic cell)
Types of Immunity
Innate Immunity Adaptive Immunity
• Non-specific
• All plants & animals
• Pathogen-specific
• Only in vertebrates
• Involves B and T cells
Adaptive Response Lymphocytes (WBCs): produced by stem cells in bone marrow
T cells: mature in thymus
helper T, cytotoxic T
B cells: stay and mature in bone marrow
plasma cells antibodies
Antigen: substance that elicits lymphocyte response
Antibody (immunoglobulin – Ig): protein made by B cell that binds to antigens
Humoral Immune Response
(antibodies)
Cell-Mediated Immune
Response
(T Cells)
Antigen-presenting
cell
Helper T cell
B cell Cytotoxic T cell
Plasma cell
Infected cell
Antibodies
Identify and
destroy
tag for
destruction
pathogen
4/14/2016
18
Immunological Memory Primary immune response: 1st exposure to antigen
Memory cells:
Secondary immune response: repeat exposure faster, greater response AP Bio Exam Review
Ecology Unit
Ecology: the scientific study of the interactions between organisms and the environment
• The ecological study of species involves biotic and abiotic influences.
– Biotic = living (organisms)
– Abiotic = nonliving (temp, water, salinity, sunlight, soil)
Heirarchy
• Organisms
• Population: group of individuals of same species living in a particular geographic area
• Community: all the organisms of all the species that inhabit a particular area
• Ecosystem: all the abiotic factors + community of species in a certain area
• Biosphere: global ecosystem
Clumped. For many animals, such as these wolves, living in groups increases the effectiveness of hunting, spreads the work of protecting and caring for young, and helps exclude other individuals from their territory.
Uniform. Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors.
Random. Dandelions grow from windblown seeds that land at random and later germinate.
Patterns of Dispersal:
1. Clumped – most common; near required resource
2. Uniform – usually antagonistic interactions
3. Random – not common in nature
Survivorship Curves:
• Type I curve: low death rate early in life (humans)
• Type II curve: constant death rate over lifespan (squirrels)
• Type III curve: high death rate early in life (oysters)
4/14/2016
19
• Zero population growth: B = D
• Exponential population growth: ideal conditions, population grows rapidly
Number of generations
Po
pu
lati
on
siz
e (
N)
2,000
= 1.0N
1,000
1,500
500
0 15 10 5 0
dN dt
= 0.5N dN dt
• Unlimited resources are rare
• Logistic model: incorporates carrying capacity (K)
– K = maximum stable population which can be sustained by environment
• dN/dt = rmax((K-N)/K)
• S-shaped curve
• K-selection: pop. close to carrying capacity
• r-selection: maximize reproductive success
K-selection r-selection
Live around K Exponential growth
High prenatal care Little or no care
Low birth numbers High birth numbers
Good survival of young Poor survival of young
Density-dependent Density independent
ie. Humans ie. cockroaches
Factors that limit population growth:
• Density-Dependent factors: population matters
– i.e. Predation, disease, competition, territoriality, waste accumulation
• Density-Independent factors: population not a factor
– i.e. Natural disasters: fire, flood, weather
Microorganisms and other
detritivores
Tertiary consumers
Secondary consumers
Detritus Primary consumers
Sun
Primary producers
Heat
Key
Chemical cycling
Energy flow
4/14/2016
20
Primary Production
• Total primary production is known as gross
primary production (GPP).
– This is the amount of light energy that is
converted into chemical energy.
• The net primary production (NPP) is equal to
gross primary production minus the energy used
by the primary producers for respiration (R):
– NPP = GPP – R
• NPP = storage of chemical energy available to
consumers in an ecosystem 1,000,000 J of sunlight
10,000 J
1,000 J
100 J
10 J Tertiary
consumers
Secondary
consumers
Primary
consumers
Primary
producers
10% transfer of
energy from one
level to next
Matter Cycles in Ecosystem
• Biogeochemical cycles: nutrient cycles that contain both biotic and abiotic components
• organic inorganic parts of an ecosystem
• Nutrient Cycles: water, carbon, nitrogen, phosphprus