EE5 Flashcards
What is a haplotype?
Set of DNA variations or polymorphisms inherited together.
-Combination of alleles or set of SNP’s found on the same chromosome.
What is a haplogroup?
group of similar haplotypes that share a CA having the same SNPs in all haplotypes
What is linkage disequilibrium?
The combination of alleles more often would be expected from random formation of haplotypes.
The non random association of alleles at 2 or more loci, descend from CA
What is Linkage?
Tendancy of alleles to be inherited together during meiosis
What is Linkage equilibirum?
combination of alles or genotypes found in expected proportions
What is a Selective Sweep?
Reduction in variation among nucleotides in neighbouring DNA of a mutation as a result of recent and strong positive natural selection
What happens if there is a strong selective sweep?
region of genome where pos selected haplotype is is essentially the only one that exists in a population. results in reduction of variation.
What does Natural Selection cause?
- loss of genetic diversity around selected site.
- Increased linkage disequilibrium around selected site
- excess of most common allele
- deficiency of intermediate frequency alleles
- LD decays with time since selection began
Vp=
Vp= Ve+ Vg Vp= phenotypic variance Vg= genetic variation Ve= environmental variance
Va=
Va=Vg
Va= additive genetic variance dependent on magnitude of effects
for quanititive values
When testing for selection what is the null hypotheiss?
Genetic Drift
What is associated with the ability of digest milk as adults?
SNP in gene encoding lactase.
3 identified SNPs associated with lactase persistence and have derived alleles that significatnly enhance transcription from LCT(Lactase) promoter
What is heritability?
proportion of variation explained by genetics
h2=va/vp
correlation between mean of parents and offspring.
How does the frequency of lactase persistence change across the world?
decreases North West- South East
