Quest 3 Flashcards
segregation
each individual has 2 copies at each lotus and they segregate during gamete production so only one copy goes into each gamete
independent assortment
allele that is passed down to next generation at one lotus is independent of which allele is passed down to the next generation at another lotus
particulate inheritance
passes down across generations even when they are not vividly expressed in offspring
blended inheritance
the two traits are mixed together
genetic code
the way in which 20 amino acids and stop signals are specified by the 64 possible codons
redundancy
the same amino acid can be coded by multiple codons
codon bias
specific codons are used more often than synonymous codons
epigentetic inheritance
experiences of the parents can be passed down to the offspring
methylation
adding on a methyl group to a substrate
histone
basic proteins found in chromatin in which DNA wraps around
NC RNA
functional RNA molecule that is not translated into a protein
four sources of variation
recombination
mutation
migration
lateral gene transfer
nonsense mutation
creates a stop codon where there wasnt one previously present
synonymous mutation
silent mutation that does not alter the amino acid
nonsynonymous mutation
base change that changes amino acid sequence
insertion mutation
addition of one of more nucleotides
deletion mutation
removal of one or more nucleotides
frameshift mutation
insertion/deletion occurs outside a multiple of 3 nucleotides which affects the translation of codons and protein production
crossing over
physical exchange of DNA sements
chromosomal duplication
section of a chromosome is duplicated causing a change in ploidy
translocation
section of one chromosome moves to another
ploidy
number of sets of chromosomes, haploid 1, diploid 2
gene duplications
duplications of regions of DNA that contain entire genes
deleterious mutation
change in DNA sequence that causes a risk of developing a certain genetic disorder or disease
hardy-Weinberg equilibrium
makes inferences about evolutionary processes and genotype frequencies when NS and other changes arent occurring
selection acts on _____ and changes ______
individuals, populations
HWE conclusions
-frequencies do not chnage over time in absence of evolutionary process
-equilibrium genotype can be predicted by using allele frequencies and random mating when evolution is not occurring
-locus that is not in HWE will reach HWE in one generation if no evolution occuring
assumptions of HWE
- NS not operating
- mating is random
- no mutation
- no migration in/out
- infinite population size
selection coefficient (s)
measure the strength of NS for/against a specific genotype of phenotype
frequency independent selection
fitness associated with a trait is not dependent on the frequency of the trait in a population.
frequency independent selection example
mice and autoimmune diseases. representing underdominace
frequency dependent selection
costs/benefits associated with trait depend on frequency in the population, can be positive or negative
frequency dependent selection example
snails and shell directions. Snails can only mate with snails with shells that coil in the same direction
directional selection
one allele is consistently favored over the other and eventually the favored allele will become fixed in the population
stabilizing selection
as a trait is stabilized in the population, genetic diversity decreases
disruptive selection
individuals with intermediate phenotype are less fit than those of both higher and lower phenotype
overdominance/heterozygote advantage
heterozygous genotype has a higher fitness than both homozygous genotypes
balanced polymophism
stable equilibrium where both alleles are present
balancing selection
allele frequencies will return to equilibrium values after veering away from equilibrium
stable equilibrium
system does not change and if displaced it moves back to its original position
underdominance/heterozygote disadvantage
heterozygote genotype has less fitness than both homozygote genotypes
positive frequency dependent selection
phenotype is favored once it becomes common in the population
negative frequency dependent selection
fitness associated with a trait decreases as frequency of the trait increases
viability selection
fitness differences that arise due to differences in survival and mortality rate
fecundity selection
NS acting on number of offspring produced
assortative mating
individuals mate with those of same genotype and phenotype
disassortative mating
individuals mate with those of different genotypes and phenotypes
identical by descent
identical because of shared descent through a recent ancestor
inbreeding
individuals mate with genetic relatives
inbreeding depression
offspring from matings between genetic relatives have a reduced fitness
migration
movement from one habitat to another in search new/better conditions
NS population genetic process
variation in pop decreases, variation between pop increases
mutation population genetic process
variation in pop and between pop increases
nonrandom mating pop genetic process
variation in and between pop have no effect on allele frequencies
migration pop genetic process
variation in pop increases, between pop decreases
positive mutation
frequency increases through NS
mutation selection balance
if NS decreases the frequency of an allele, its balanced by producing more mutations of the other allele
discrete traits
maintain a distinct phenotype
