Question

Suppose that allele D produces tiny ears and allele d produces normal ears. A heterozygous male with the Dd genotype mates with a homozygous female with the dd genotype. Tiny ears is an autosomal dominant trait expressed with 50% penetrance. Determine the probability that their offspring will have tiny ears. Report your answer as a percentage without decimal points.

Answer 1

There will be 25% of the offspring with tiny ears.

Step-by-step explanation:

An autosomal trait is caracterized for having its allele located in a locus of an autosome, it mean a non sexual chromosome. When it is an autosomal dominant trait it means that dominant homozygous and heterozigous will express the phenotype asociated to the dominant alele.

The concept of penetrance refers to that situations in which only a percentage of the offspring that has a particular genotype, effectively express the corresponding phenotype.

In the present case we have Dd x dd, so the offspring will be: Dd, Dd, dd and dd. According to this, there will be 50% of the offspring with tiny ears. But, ss the Tiny ears is an autosomal dominant trait expressed with 50% penetrance, only half of the offspring with the alele D, will express the phenotype, this is 25%.