Poopulation Genetics Flashcards
What is evolution?
Change in genotype frequencies over time
What is a locus?
Place on a chromosome where a gene is located
What is an allele?
The DNA at a particular locus
What is the frequency of allele p or q in a population? (Think the math)
F(A/A) + F(A/a)/2
What is hardy weinberg equilibrium?
p^2 + 2pq + q^2 = 1
What does hardy Weinberg assume?
Random mating, infinite population size, no mutation, no migration, and no selection
If the frequency of each allele (A1A2) is 1/2, what are the odds of keeping both alleles after t generations?
1/2^t
What will happen to allele frequencies if there are no new mutations?
Eventually one will fix
What is a population bottleneck?
Singling out a segment of the population (prob via natural disaster) which decreases genetic variation
What is positive selection?
An allele is favored
What is purifying selection?
Removing deleterious alleles
What is balancing selection?
Favors heterozygous to maintain diversity
What is a haplotype?
A combination of alleles on a single chromosomes
What is linkage equilibrium?
Association between alleles is random and there is equal chance for each possible haplotype
What is linkage disequilibrium?
Not random associated alleles (ex. You can have AB Ab and ab but not aB)
What causes linkage disequilibrium? What causes it to disappear over time?
Mutations, recombination
What is selective sweep?
When an advantageous part of a haplotype arises, any alleles close to it in the chromosome will be selected for with that advantageous part
What is neutral theory?
Most evolutionary changes aren’t based on advantageous selection but rather random fixation of selectively neutral or nearly neutral mutants through genetic drift
What is some evidence to support neutral theory?
- conservative amino acid substitutions are more common
- synonymous base substitutions are more frequent
- no coding sequences change at a higher rate
What are the two ways DNA transposons can increase their copy number?
Repair (cuts and pastes itself somewhere and then the place it leaves empty is repaired with a new copy) and replication (gets replicated during DNA replication then one copy move ahead to get replicated again)
What are the two types of transposition?
Replicative (copy) and Conservative (cut)
How does a retrotransposon work?
> Transposon is transcribed
Endonuclease binds to target DNA site with the RNA
Endonuclease cleaves the target DNA site
Reverse transcriptase reverse transcribes the transposon
Other side of DNA will gain the transposon via repair
