Question

In Mexico, about 16% of the population is left handed. The allele for left handedness is recessive to right handedness. If 2000 fans attended a football match, how many would you expect to have the three possible genotypes (RR, Rr, rr)?

Answer 1

720 fans will have the RR genotype

960 fans will have the Rr genotype

320 will have the rr genotype

Step-by-step explanation:

The allele for left handedness (r) is recessive to right handedness (RR).

The possible genotypes and phenotypes for this gene are:

• RR: right handed
• Rr: right handed
• rr: left handed

If we assume the population in Mexico is in Hardy Weinberg equilibrium, the frequencies of each genotype will be:

• RR : p²
• Rr: 2pq
• rr: q²

Where p is the frequency of the R allele and q is the frequency of the r allele.

The frequency of the left handed population (with rr genotype) is 0.16, therefore q² = 0.16.

q² = 0.16

q = √0.16

q=0.4

Since there are only two alleles, p + q = 1.

Then, p = 1-q = 0.6

Now we can calculate the expected number of people with each genotype in the football stadium with 2000 people:

• RR genotype = p² * 2000 = 0.6²*2000 = 720
• Rr genotype= 2pq * 2000 = 2*0.6*0.4* 2000= 960
• rr genotype= q² * 2000 = 0.4² * 2000 = 320