1. Evolution and Populations –Essential Questions p. 431-435
How can a lethal gene exist in a gene pool and not disappear?
What is genetic drift?
Explain each of the three different types of genetic drift.
According to the Hardy-Weinberg Principle, what five things must occur to prevent genetic drift?
5. When do mutations pass from one generation to the next?

2. Population Genetics

3. Alleles that are lethal in a homozygous individual may be carried in a heterozygote and thus maintained in a gene pool. Know the conditions for Hardy-Weinberg equilibrium in a population and why these conditions are not likely to appear in nature. Know how to solve the Hardy-Weinberg equation to predict the frequency of genotypes in a population, given the frequency of phenotypes.

4. – genes have at least two alleles
Genetic Variation
– genes have at least two alleles
Gene Pool – all genes, including all of the different alleles, present in a population

5. Relative Frequency
– the number of times an allele occurs in a gene pool compared with the number of times other alleles for the same gene occur
-  evolution is any change in the relative frequency of alleles in a population

6. Genetic Drift Stabilizing selection Disruptive Selection
Directional Selection

7. Lethal genes remain in a gene pool at low frequency if they are recessive. They are carried by hybrids (heterozygous individuals).

8. Sources of Genetic Variation
Mutations – changes in a DNA sequence
- additions, deletions, substitutions of nucleotides, and rearrangement of chromosomes
neutral, harmful, or beneficial
to be passed on they must be in sex cells

9. Hardy-Weinberg Principle
Genetic Equilibrium – allele frequencies remain
constant as long as there remains:
1.  random mating
2.  a very large population
3. no movement into or
out of the population
4.  no mutations
5. no natural selection
*** NOT likely to happen in nature

10. p2 + 2pq + q2 =1 p + q = 1 2pq = % of Aa q2 = % of aa
p2 = % of AA
2pq = % of Aa
q = % of aa
q = # of a alleles
p = # of A alleles

11. Use the chart to determine the frequency of the AA genotype
Use the chart to determine the frequency of the AA genotype. What is the frequency of the A allele?
Flowers(population 100)
AA Aa aa