LECTURE FIVE

define haplotype

the combination of genes (loci) on one chromosome

what are recombinant gametes

gametes which do not represent either of the parental cells

what are parental gametes

gametes which represent a parental cell

what is the recombination fraction

the proportion of recombination gametes after meiosis

why is recombination important

natural selection can act on combinations of alleles

recombination works to create and break up combinations

define linkage equilibirum

random association of alleles at different loci

define linkage disequilibrium

non-random association of alleles at different loci

what can cause linkage disequilibrium

genetic drift in small populations

bottleneck effect

natural selection that favours association of 2 genotypes

what destroys linkage disequilibrium

recombination

what does the frequency of 2 locus haplotypes depend on

frequency of the 2 alleles

amount of recombination between the 2 alleles

what does r represent

rate of recombination

what does 1 - r represent

rate of non-recombination

does chromosome recombination occur equally everywhere

no, chromosome recombination in meiosis does not occur with equal probability at all loci on human chromosomes

is linkage disequilibrium uniform

no, linkage disequilibrium is not uniform over the length of a chromosome

explain the relationship between regions of linkage disequilibirum and recombination

a region of high linkage disequilibrium corresponds to a region of low recombination and vice versa

explain epistasis

when 2 or more different genes interact to produce a phenotype that is not an additive effect of the genes

the effect of 1 allele is maksing/modifying the effect caused by expression of one or more other loci