4.5 Allele Frequency and Hardy-Weinberg Flashcards
4.5 i) Understand how the Hardy-Weinberg equation can be used to see whether a change in allele frequency is occurring in a population over time. (17 cards)
What is allele frequency?
how often an allele occurs in a population
How is allele frequency represented?
- number between 0-1
- as a percentage
How is allele frequency related to evolution?
when there is a change in allele frequency in a population over time, evolution has occurred
How are new alleles introduced in a population?
by mutations in genes
What is a gene pool?
a gene pool consists of all the alleles of all the genes present in a population
Why is having a large gene pool advantageous?
- populations with a large gene pool have greater genetic diversity
- so are more likely to possess alleles that allow them to survive
What is the Hardy-Weinberg principle?
the principle predicts that the frequencies of alleles in a population won’t change from one generation to the next
What are the conditions of the Hardy-Weinberg principle?
- no immigration and emigration
- no mutations
- no natural selection
- there must be random mating (all possible genotypes can breed with all others)
If allele frequencies do change between generations in a large population, what has happened?
- immigration
- emigration
- natural selection
- mutation
What are the Hardy-Weinberg equations?
- p + q = 1
- p2 + 2pq + q2 = 1
What is p and q (in the Hardy-Weinberg equation)?
p = the frequency of the dominant allele
q = the frequency of the recessive allele
What is p2, 2pq, and q2 (in the Hardy-Weinberg equation)?
- p2 = the frequency of the homozygous dominant genotype
- 2pq = the frequency of the heterozygous genotype
- q2 = the frequency of the homozygous recessive genotype
Which Hardy-Weinberg equation can be used to predict allele frequency?
p+q=1
Which Hardy-Weinberg equation can be used to predict genotype frequency?
p2 + 2pq + q2 = 1
How can phenotype frequencies be predicted using the Hardy-Weinberg equations?
the frequency of the dominant phenotype = p2 + 2pq
the frequency of the recessive phenotype = q2
If the actual frequency of an allele is different to the predicted frequency of an allele (from the HW equations), what does this suggest?
factors affecting allele frequency like immigration, emigration, natural selection, and mutation are present
How can the Hardy-Weinberg equation be used to see whether a
change in allele frequency is occurring in a population over time?
if the actual frequency of an allele in a population is different to the predicted frequency, then this indicates a change
