Population genetics Flashcards
What is the locus?
The physical position of a gene or marker along a chromosome
What are alleles?
Different forms of a gene
How is the genotype formed?
Made by two alleles in a diploid organism
What is a Homozygote?
Individual with two identical alleles
What is a heterotrophic zygote?
Individual with two different alleles
What is a polymorphism?
A gene or phenotype with more than one form
What does population genetics study?
The frequencies of alleles in a population in order to understand the factors that determine the gene composition a population and the genetic basis etc of genetic diseases
How are allele frequencies represented?
One as p, the other as q
What is the Hardy Weinberg principle?
the frequencies of alleles and genotypes in a population will remain constant from generation to generation, provided that only mendelian segregation and recombination alleles are at work
When is the gene pool in HWE?
When there is no change in gene frequency, population isn’t evolving
What are the conditions for HWE?
Random mating No natural selection No mutation No migration Large population size
Why is HW useful?
Provides a description of how genetic material is maintained and used to show how blending inheritance doesn’t happen
What does a departure from HWE mean?
Some of the conditions are not being met, something is acting on the population
What are the steps involved in testing for departure from HWE?
1) Estimate allele frequency 1 = p+q
2) Calculate the expected genotype frequency under HWE -
3) Calculate expected genotype counts in sample
4) Calculate chi squared statistic
Using the chi squared value, how can you tell if a population is in HWE?
Larger value means larger departure from expectation - if larger than the threshold, not in HWE, if smaller, then in HWE
