cumulative final review Flashcards
1: why is virus sometimes considered living, and sometimes not?
virus is an obligate parasite (not on tree of life)
1: evolution of drug resistance in HIV
random mutations create variations in AZT resistance
high rate of mutation due to reverse transcriptase enzyme
1: characteristics of scientific theory
must be both testable and falsifiable (some possible observation or experimental finding could prove the theory to be wrong)
1: evolution is variational/transformational?
variational: populations evolve, individuals do not.
change through time
change over a long period of time. allele frequencies in a population change from one generation to the next. (due to environmental pressures?)
common ancestry
all life is related through common ancestry
speciation
creation of a new species. species can reproduce with viable, fertile offspring
gradualism
species evolve through slow continuous changes without significant interruption
natural selection
organisms that are better fitted to their environment are more likely to survive and pass on their genes to their offspring.
G1 phase
period of growth before DNA replicates. gap where no DNA is synthesized, cell continues to function
S phase
DNA replication and chromosome duplication occur. continues synthesis of other cellular molecules
G2 phase
second gap where cell growth continues and cell prepares for mitosis. no DNA synthesis, continues to synthesize RNAs and proteins. marks the end of interphase
G1-S checkpoint
before replication, ensures mutations are not duplicated, if severe DNA damage then cell proceeds to G0 phase
G-M checkpoint
ensures that cell is prepared for mitosis. all necessary conditions are met to prevent errors in chromosomes segregation and cell division
mitotic spindle checkpoint
ensures equal distribution of sister chromatids to minimize the risk of aneuploidy
2: positive regulation
phosphorylation cascade - cyclins and CDKs
cyclin binds to CDK
cyclin-CDK complex is phosphorylated
activated cyclin-CDK complex phosphorylates target protein
phosphorylated target protein changes to active form. moves cell into next stage of cell cycle
2: negative regulation
p53 detects DNA damage and increases p21 (cyclin-CDK inhibitor) production which blocks phosphorylation of cyclin CDK. stops cell cycle
2: why is meiosis I reductional and meiosis II equational?
meiosis I: 2n → n
meiosis II: n →n
2: mechanisms giving rise to variation in meiosis
homologous recombination - crossing over at the chiasma
independent assortment - dependent on equatorial arrangement
random fertilization - any haploid cells could fuse
aneuploidy
abnormal number of chromosomes
2: products of life cycle in animals
zygote (2n) → animal (2n) (mitosis)
animal (2n) → gametes (n) (meiosis)
2: products of life cycle in plants and fungi
zygote (2n) → sporophyte (2n) mitosis
sporophyte (2n) → spores (n) meiosis
spores (n) → gametophyte (2n) mitosis
2: products of life cycle in fungi and algae
zygote (2n) → spore (n) meiosis
spore (n) → gametophyte (n) mitosis
gametophyte (n) → gametes (n) mitosis
3: n-value and coefficient of n
n-value: number of unique chromosomes present in an organism
coefficient of n (ploidy): number of unique sets present in an organism
3: C-value and coefficient of C
C-value: amount of DNA in one set of chromosomes, genome size
coefficient of C: how many time the entire genome is present in a cell
3: correlation between n and C, implications on complexity?
n and C are not correlated nor do they dictate complexity in an organism
semi-conservative DNA replication
old strand is template for synthesis for new strand.
cell senescence
irreversible cell cycle arrest. G0 phase, no longer replicates or divides
Hayflick limit
number of times a cell divides before cell division stops
3: mechanism of telomerase action
telomerase restores length of telomeres.
3: why do only cancerous and germ cells express telomerase?
telomerase could cause a problem in somatic cells (mutations)
4: types of DNA damage
exogenous, endogenous
4: exogenous DNA damage
outside, from environment, damages DNA directly.
UV light, chemicals (smoking medication, air pollution), ionizing radiation
4: endogenous DNA damage
inside cell
ROS, replication errors
4: mechanism of ROS
IR splits H2O
very unstable and electronegative
steals electrons → damage to cell
oxygen paradox
repaired by NHEJ
4: mechanism of proofreading
DNA polymerase III corrects itself (exonuclease activity)
4: mechanism of mismatch repair
mismatch repair proteins detect errors and excise and correct incorrect nucleotide
4: mechanism of NHEJ
non-homologous end joining.
repairs double strand breaks
could introduce errors → mutation
4: types of point mutations (3)
substitution: single nucleotide is replaced by another
silent - no effect on amino acid sequence
missense - changes one amino acid, potentially affecting function and structure of protein
nonsense - introduces stop codon leading to truncated polypeptide
4: frameshift mutations (2)
insertion or deletion - addition or removal of nucleotides alters genetic sequence. often leads to truncated protein
4: chromosomal mutations (2)
inversion - segment of chromosomes is reversed in orientation, potentially disrupting gene function
translocation - segments of DNA are exchanged between non-homologous chromosomes, potentially disrupting gene expression
4: thymine dimers
distort the backbone and halt DNA polymerase (not a mismatch)
caused by UV, repaired by excision repair in humans and by photolyase and white light in other species
4: role of tautomeric shifts in mutagenesis (process where DNA changes resulting in a gene mutation
normal pairing favoured, has different preferred partner when tautomeric form shifts. can result in mutation
4: transposable elements
portion of genome that copy/cut and paste somewhere else
4: regulatory role of transposable elements
responsible for increases in genome size.
4: genome composition
55% transposons, viral sequences, dead genes (junk)
25% unknown (junk?)
10% essential (2% coding)
10% intron (junk)
5: epistasis and how it differs from Mendelian genetics
expression of one gene masks the expression of another gene at a different locus. results in complex inheritance patterns that do not conform to the simple dominance and recessiveness observed in classics Mendelian genetics
6: genotypic frequency
distribution of genotypes in a population
6: allele frequency
distribution of a specific allele in a population
6: conditions of Hardy-Weinberg Equilibrium (5-6)
no mutations, all genotypes are equally fit, closed population (no gene flow or migration), infinite population size, random mating)
6: absolute fitness (W)
average number of surviving offspring for each genotype
6: relative fitness (w)
absolute fitness of one genotype divided by the absolute fitness of the most fit genotype
6: selection against dominant allele
removed from population over time
6: selection against recessive allele
decreases but never fully goes away (can hide in heterozygotes)
6: mechanisms of microevolution (agents of evolution) (5)
mutations
non-random mating
gene flow
genetic drift
natural selection
gene flow
organisms or their gametes sometimes move from one population to another and may introduce novel alleles into a population, shifting its allele and genotype frequencies away from the values predicted by H-W
genetic drift
allele frequencies change from one generation to the next simply by chance
ex. founder, bottleneck effect
6: directional selection
shifts a trait away from the existing mean and towards the favoured extreme
most cases of artificial selection are directional
6: stabilizing selection
individuals expressing intermediate phenotypes have the highest relative fitness
most common mode of natural selection. reduces genetic and phenotypic variation and increases frequency of intermediate phenotypes
6: disruptive selection
extreme phenotypes have higher relative fitness than intermediate phenotypes
less common than directional and stabilizing selection
7: why sex?
allows us to make new multilocus combinations of alleles by meiosis
7: dioecious
exclusively male or female
cross-fertilization between male and female individuals necessary for sexual reproduction
7: monoecious
both male and female reproductive parts (in same plant). organism can carry out both functions involved in sexual reproduction
7: hermaphrodite
both male and female reproductive parts (in same flower)
7: risks of selfing
negative effects of inbreeding
7: why sexual reproduction over asexual
removes harmful alleles and diversifies variety of offspring. increases chances of surviving in unstable conditions (advantageous traits)
7: intrasexual selection
competition between individuals of the same sex
7: intersexual selection
choose mate based on certain traits or behaviours displayed by opposite sex
8: morphological species concept
members of a species share similar physical traits that distinguish them from individuals of other species
8: biological species concept
members of a species can interbreed and produce viable, fertile offspring under natural conditions
8: phylogenetic species concept
shares a common ancestor and same branch on phylogenetic tree
8: prezygotic isolating mechanisms
ecological - species live in different habitats
temporal - species breed at different times
behavioural - species cannot communicate
mechanical - species cannot physically mate
gametic - species have nonmatching receptors on gametes
8: postzygotic isolating mechanisms
hybrid inviability - hybrid offspring cannot produce gametes
hybrid sterility - hybrid offspring cannot produce gametes
hybrid breakdown - hybrid offspring have reduced survival or feritility
8: allopatric speciation
between geographically isolated species
gene flow prevented
genetic differences - may cause reproductive isolation
8: sympatric speciation
same geographic area
reproductive isolation, potentially leading to the formation of a new species
8: secondary contact, reinforcement
two previously geographically isolated populations reunite. natural selection strengthens prezygotic barriers to reproduction between two divergent populations
9: use of phylogenetic tree
used to show evolutionary relationships between organisms
9: how to find common ancestor on phylogenetic tree
find the branching point of the two species. the more recent the branchign points are, the more closely related the two species are
9: monophyletic grouping given a phylogenetic tree
monophyletic: includes all descendants of MRCA of the group
non-monophyletic: includes descendants that aren’t from the most recent ancestor
homology
similarity that reflects common ancestry
convergence
not closely related organisms develop similar features through evolution
homoplasy
misleading similarities or dissimilarities, not due to common ancestry
9: principle of parsimony
simplest approach is best. minimize number of homoplasies. tree with fewer evolutionary changes will be most parsimonious
9: derived
character states that are new in descendants
9: ancestral
character states that were present in the ancestors of a clade
9: anagenesis
single species gradually undergoes evolutionary change over time into a different, more advanced form without formation of separate species
9: cladogenesis
single species diverges into two or more distinct species. increases biodiversity
9: evolutionary systematics
classifies and organizes organisms based on their evolutionary relationships
10: intraspecific interaction
interactions between individuals of the same species
10: interspecific interactions
interactions between individuals of different species
10: interference/contest competition
one organism has resource and another will fight to take it (dangerous, either party has a chance of getting hurt)
10: exploitation/scramble competition
2 or more organisms use the same resource, one uses more than others (free for all)
10: symbiosis
close and long term association between 2 species
10: symbiotic relationships (5)
mutualism(+/+)
commensalism (+/0)
predation (+/-)
parasitism (+/-)
herbivory (+/-)
10: mutualism
both species benefit from the association
10: commensalism
one species benefits from the association but the other is unaffected
10: predation
only one species benefits from the association and the prey is injured or killed (two strategies: sit and wait, active pursuit)
10: parasitism
only one species benefits from the association
affects fitness of the host, but doesn’t result in its direct death
10: parasitoids
when an adult is free living, but its offspring develop in or on the host and kill it
10: herbivory
similar to parasitism but between herbivores and plants
affects fitness of plant but doesn’t result in its direct death
10: simple (direct) parasitic life cycle
parasite species uses one host species to complete life cycle and survive
10: complex (indirect) parasitic life cycle
parasite species uses at least 2 different host species to complete life cycle and survive
10: host manipulation by parasites and parasitoids
parasite-induced alteration of a host’s phenotype that increases parasite fitness. improves probability of transmission
10: red queen hypothesis
species must constantly adapt and evolve in competition with other evolving organisms. environment is constantly changing
10: continuous arms race
ongoing competition between different species in an ecosystem, where each species evolves adaptations and counter-adaptations to gain an advantage. can only be a result of chance mutations
10: adaptations to reduce enemy impact (10)
physical
behavioural
autonomy
chemical
camouflage
mimesis
bodyguards
herd effect
detection of predators
synchronized emergence
10: ecology of fear
interactions with predators may not result in death, it can change behaviours
10: keystone species
removal of a keystone species in an ecosystem can lead to a disruption of the entire food web
10: intraguild predation
species compete for same prey and would benefit from preying upon potential competitors
11: anthropocene
current geological age in which humans have been the dominant factor on climate and the environment. started by the industrial revolution
11: tipping point
1.5C, point of no return for irreversible climate change
11: increasing climate trends (7)
global surface temperature (land and ocean)
ocean heat content
carbon dioxide
sea level
methane
nitrous oxide
specific humidity
11: decreasing climate trends (3)
arctic and antarctic sea ice extent
global glacier mass balance
greenland ice sheet mass balance
11: drought conditions
decreased foraging
decreased flower availability
higher nectar viscosity
more competition with resident nectivores
11: selection effects of a changing environment
peppered moths and univoltine (know specifics)
11: gradual change
climate change - opportunity for adaptation or slow displacement
11: sudden change
extreme weather events - no opportunity for adaptation
11: tropicalization
movement of organisms in response to warmer temperatures from tropical (warmer) to temperate (cooler) environments
effects on food chains, gain/loss of genetic diversity, hybridization
11: geographical changes (3)
latitudinal
altitudinal
aquatic depth
11: latitudinal change
species’ geographic range can become more North/South over time (tropicalization)
11: altitudinal change
ex. tropical birds are moving to higher altitudes as a result of climate change
11: aquatic depth
distribution of species is changing according to sea levels
11: asynchrony
species present at a different time that its food source
