Genetics Variation and Population

Question 1

1.

4 Factors that affect frequency of variants in a population

1. […]
2. […]
3. […]
4. […]

Answer 1

4 Factors that affect frequency of variants in a population

1. Selection
2. Mutation
3. Genetic Drift
4. Gene flow

Selection (positive and negative) (evolution theory)
eg.
- lactase for drinking milk
- adaptation to high altitudes
- survival against malaria/HIV

Mutation
- Occurs over a very large population. so a very small effect on population’s allele frquency

Genetic drift
- over a small population esp.
- happens by loss of some alleles and over-representation of others
- bottleneck effect (adverse event killing many and leaving a few left to re-populate)
- founder effect (when a population traces back to common ancestors)

Genetic flow
- ppl migrating into a population and mix their gene pool.

Question 2

Sickle Cell anemia is positively selected in the gene pool because […]

Answer 2

Sickle Cell anemia is positively selected in the gene pool because **the heterozygotes are resistant to the malarial parasite which kills a large number of people each year. **

THE CARRIERS ARE ADVANTAGED
THE PPL WITH DISEASE (AR) SUFFER

This is an example of balancing selection between the fierce selection against homozygous sickle-cell sufferers