Topic 6 qualitative genetics Flashcards
Population gentics is …
the study of how allelic and genotypic fequenies change in populations overtime
A species is…
a group of individuals that are normally able to interbred within the group, but not with individuals outside of the group.
A population is…
a group of individuals of one species that are together at the same time and place, and hence able to interbreed regularaly.
A gene pool is …
all the genes available within a population.
Speciation is …
the process by which one species splits into two. can only occur when the gene pool of the species has been divided into two or more gene pools and a mechanism that has evolved that prevent sexual reproduction between the two gene pools.
A centre of diversity is …
a region where a high number of strains within a species coexist
How do you calculate allelic frequencies?
p+q=1
since homozygotes have two of each allele and heterozyotes have only one, and since the total number of alleles is twice the number of individuals, we can calculate allelic frequenices like:
eg MN blood groups.
Type M (MM genotype) = 114
Type MN (MN genotype) = 76
Type N (NN genotype) = 10
Total = 200
Then:
p=f(M)= 2 x 114 + 76 304
——————- = ——- = 0.76
2 x 200 400
q=f(N)= 2 x 10 + 76 96
—————- = —— = 0.24
2 x 200 400
How do you calculate the proportions of each genotype we would expect to find in the next generation?
f(MM) = p^2 = (0.76)^2 = 0.5776 f(MN) = 2pq = 2 x 0.76 x 0.24 = 0.3648 f(NN) = q^2 = (0.24)^2 = 0.0576
What is the hardy weinberg equilibrium calculation?
To check whether a population is at hardy weinburg equilibrium we use the following calculation, a chi-square test. This chi square test uses accepted statistical laws to see if the variation from expected is statistcally significant.
x^2 = (O - E)^2
————
E
