Suppose that allele D produces tiny toes and allele d produces normal toes. A heterozygous male with the Dd genotype mates with a homozygous female with the dd genotype. Tiny toes is an autosomal dominant trait expressed with 30% penetrance. Determine the probability that their offspring will have tiny toes. Report your answer as a percentage without decimal points.

Respuesta :

The right answer is 15%.

The D allele is dominant, ie in the case of heterozygosity, it is expressed.

When we cross between the male and the female. we will have 50% "Dd" and 50% "dd".

50% (frequency of 0.5) of the descendant will carry the dominant gene but only 30% (frequency of 0.3) among them will express the disease, therefore it is necessary to make the multiplication:

0.5 * 0.3 = 0.15 (equivalent to 15% of the descendence).