24 Population Genetics Flashcards
what is the definition of gene pool?
all variants of a gene within a population
what is the definition of genetic bottleneck?
a drastic reduction in population numbers
what is the definition of the founder effect?
a small group breaks away from the original population, causing allele(s) to become more/less common in the group
what are the two types of isolation in speciation?
geographic (allopatric): involves a physical barrier, which causes the two groups to experience different selection pressures
reproductive: results from geographic isolation. mechanisms include: temporal, behavioural, anatomical and post-mating barriers
what is the Hardy-Weinberg principle?
the proportion of alleles will remain constant from one generation to the next, providing the following conditions are met:
- no new mutations
- no flow of alleles (due to migration)
- no natural selection
- large population
- random mating
give the two Hardy-Weinberg equations
p + q = 1.0
p^2 + 2pq + q^2 = 1.0
where: p = frequency of dominant q = frequency of recessive p^2 = frequency of homozygous dominant 2pq = frequency of heterozygous q^2 = frequency of homozygous recessive
what is the definition of epigenetics?
the study of changes in gene expression that are not a result of changes to DNA sequence
what is the purpose of epigenetic changes?
allows expression of only the genes required for functioning
describe two mechanisms of epigenetic changes
DNA methylation:
-CH(3) groups added to DNA (usually cytosine bases) –> decreased gene expression by preventing transcription
histone modification:
DNA associated with histones for packaging and ordering
addition of acetyl/methyl/phosphate groups –> activation/deactivation of gene –> more/less accessible to transcription
what is the purpose of natural selection?
to increase the frequency of beneficial alleles in a population
