Question

Using a Punnett square, work out the distribution of an autosomal phenotypic feature in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.

Hint:

In a cross between a homozygous dominant female and a heterozygous male, 50% of the offspring will be heterozygous and 50% will be homozygous dominant, all exhibiting the dominant trait.

Answer 1

Punnett Square: Autosomal Phenotypic Distribution

This Punnett square demonstrates a cross between a homozygous dominant female (AA) and a heterozygous male (Aa) for a single gene.

Punnett Square:

	A (from female parent)	A (from female parent)
A (from male parent)	AA	AA
a (from male parent)	Aa	Aa

Genotypic Distribution:

• 50% AA (homozygous dominant genotype)
• 50% Aa (heterozygous genotype)

Phenotypic Distribution:

Given that both the AA and Aa genotypes result in the dominant phenotype, 100% of the offspring will display the dominant characteristic.