Question

Procedure B

1. Enter you class data from the previous Wisconsin Fast Plant lab in the table below.

Phenotype	# Observed
Purple stems	118
Green stems	54

2. Use the data in the table above to calculate p and q.

(Recall that green = anl/anl = q²)

We can use the H-W equation to figure out what the frequency of each allele is even though we don’t know for certain how many heterozygotes are in the 118 total.

q² = 54/172

q= q ² = 54/172

p = ______________ q = ______________

3. If this population of B. rapa Wisconsin Fast Plants was in HWE, what would the expected genotype frequencies be for ANL/ANL, ANL/anl, anl/anl? Again notice that you need to calculate the frequencies of each genotype, based on the p and q value you determined above.

(p²)                        (2pq)                          (q²)

ANL/ANL: ________   ANL/anl: ________     anl/anl: ________

4. What would happen to the frequency of the anl allele if the green phenotype (anl/anl) became favored in a population?

5. Conversely, what would happen to the frequency of the anl allele if selection strongly favored the purple phenotype? Why would it be difficult for the anl allele to be lost completely?

Answer 1

Green trait frequency = q^2 = 54/172 = 0.314

Frequency of recessive allele = q = SQRT of 0.314 = 0.56

Frequency of dominant allele = p = 1-0.56 = 0.44

Expected genotype frequencies:

ANL/ANL = 0.44 * 0.44 = 0.1936

ANL/anl = 2*0.44 *0.56 = 0.4928

anl/anl = 0.56 * 0.56 = 0.314

The frequency of the anl allele would be increased, if the green phenotype (anl/anl) became favored in a population.

The frequency of the anl allele would be decreased, if selection strongly favored the purple phenotype.

When purple phenotype is favored, the green phenotype would become disappear. Slowly, the anl allele will become disappear.