b51 midterm 2 Flashcards
what are the three molecules that are important for evolution?
protein
DNA
RNA
an essential macromolecule for all known forms of life. ______ are three-dimensional biological polymers constructed from a set of 20 different monomers called amino acids
proteins
- most of the dry weight of a cell is composed of proteins
- give cell most of its structure
- carry out many of the chemical reactions essential for life
- there are 100 000 kinds of proteins that make up the human body but they come from a combination of 20 different amino acids
DNA is composed of compounds called
nucleotides
the structural unit that links together to form DNA (and RNA).
each ______ includes a sugar (like deoxyribose) and a base
nucleotide
any change to the genomic sequence of an organism
mutation
- may generate heritable changes to the sequence of bases in molecules of DNA
- can alter structure, physiology, or behaviour of organisms
- they can be deadly or benign (not harmful in effect)
do all living things use DNA as their genetic material?
no most do except RNA viruses which hijack DNA bearing cells to replicate themselves
a group of interacting and potentially interbreeding individuals of a species
population
- some populations span large geographic ranges while some occupy only small ranges and are isolated from other populations of the same species
- made up of individuals and those individuals carry alleles
the study of allele distributions and frequencies is known as
population genetics
study the patterns of allelic diversity in populations and how these patterns change over time
population genetics
refers to the combination of alleles carried by an individual at a particular genetic locus, or just a few loci
genotype
because diploid organisms carry two copies of each autosomal chromosome, they can have up to _____ alleles for each gene or locus
two
individuals carrying two different alleles are _______ for the locus
heterozygous
individuals carrying two copies of the same allele are ____ at the locus
homozygous
is a type of phenotypic plasticity where a single genotype can produce multiple distinct phenotypes in response to environmental cues.
polyphenism
group of individuals of same species living in the same area
population
- interbreed, producing fertile offspring
study of processes that change allele and genotype frequencies in populations
population genetics
versions of genes
alleles
combinations of alleles possessed by individuals
genotypes
observable traits
phenotypes
change in allele frequencies are driven by what four processes?
- Mutation
- Genetic drift
- Gene flow
- Natural selection
modifies allele frequencies by continually introducing new alleles
mutation
causes allele frequencies to change randomly
genetic drift
all alleles from all gametes go into a single group
gene pool
what is the Hardy Weinberg theorem based on
gene pool concept
what does the Hardy-weinberg theorem act as
a null hypothesis
Hardy-Weinberg theorem predicts that allele frequencies will NOT change in the absence of drift, selection, mutation, and migration
the study of how and why allele frequencies change
Population genetics
allelic effects can be predicted by summing number of copies present
additivity
dominant allele masks presence of recessive allele in heterozygotes
dominance
moving alleles between population
gene flow also called migration
what is the only mechanism that leads to adaptation
natural selection
mendelian genetics approach breeds two individuals that are
heterozygous
Aa x Aa
what is the fundamental equation of the Hardy Weinberg Principle
p2 + 2pq + q2 =1
when no change in allele frequencies
Hardy-Weinberg equilibrium
- allows us to predict future frequencies
**when alleles are transmitted via meiosis and random combination of gametes, the allele frequencies do not change, genotype frequencies may change but not allele frequencies
genetic drift has significant evolutionary effects in what size of populations
genetic drift has significant evolutionary effects in SMALL populations
probability of an allele surviving a bottleneck depends on
- frequency of allele before bottleneck
- severity of bottleneck (i.e. number of surviving)
survival and reproductive success of an individual with particular phenotype
biological fitness
beneficial effects for one trait but detrimental effects for another trait of that gene
antagonistic pleiotropy
multiple phenotypic traits associated with single gene
pleiotropy
selection is more powerful in ______ populations
large
does selection act on additivity of dominance
additivity
some forms of selection can maintain diversity in population
balancing selection
common phenotypes selected against; rare phenotypes are favoured
Negative frequency dependent selection:
measure of population differentiation
FST
study of genetic mechanisms and evolution of continuous, complex phenotypic traits
Quantitative genetics
Simple/discrete traits
qualitative
Complex traits
quantitative
proportion of the total phenotypic variation of a trait that is attributable to genetic differences among individuals
Broad sense heritability (H2):
the component of variance that causes offspring to resemble their parents and causes populations to evolve predictably in response to selection
narrow sense heritability
allele at one locus is independent of presence or absence of allele at second locus
Linkage equilibrium (LE)
allele at one locus is non randomly associated with the presence or absence of allele at second locus
Linkage disequilibrium (LD)
group of functionally related genes close enough to segregate as a unit
supergene
Phenotypes vary depending on environment
Phenotypic plasticity:
tracking history of alleles through time
coalescence
what is responsible for most molecular evolution
drift (said by the neutral theory of molecular evolution)
Amino acid sequence of the protein is unchanged
- Often selectively neutral
Synonyms (silent) mutation:
Amino acid sequence of the protein is changed
Likely subject to selection
Nonsynonymous (replacement) mutation
do nonsynonymous and synonymous mutations evolve at different rates if so which is faster
they evolve at different rates
synonymous mutations evolve faster (because of drift)
nonsynonymous mutations evolve slower because they are acted on by selection
the elimination of polymorphism near a beneficial mutation that has spread to fixation
Selective sweep
rate of nonsynonymous to synonymous substitutions
dN/dS
does selection act on the population or the individual
individual
Upstream section of DNA
gene control region, sometimes the promoter region, influences transcription
Acts like a light switch- turns sequences on or off
transcription factor
how are hox gene arranged
hierarchical, arranged in order of expression
capable of carrying out more than 1 function are especially likely to take on new functions if duplicated
Pleiotropic genes
homologous gene arising from gene duplication
Paralog
homologous gene in different species that originated in common ancestor
Ortholog
co-option of gene or network for novel function as result of mutation
Gene recruitment
what event happened first in the evolution of snake venom?
duplication of the defensin gene
the condition that occurs when a mutation that causes beneficial effects for one trait also causes detrimental effects on other traits is called
antagonistic pleiotropy
