Achondroplasia is an autosomal dominant genetic disorder in humans. If a man with Achondroplasia ( heterozygous) and a normal woman have children, what will be their genotypes and phenotypes?

Answer and Explanation:

Achondroplasia is a form of dwarfism that affects the formation of cartilage; early in development, most of the skeleton is comprised of cartilage. Cartilage is a type of flexible, tough tissue; in achondroplasia ossification (conversion of cartilage to bone) is affected. Symptoms include an enlarged head, shorter upper and lower limbs, and limited motion at the elbow.

Punnett squares are illustrations that display the product of hybrid trait crosses by genetic breeding.

For this cross...

Assuming Achondroplasia= dominant

Parent generation or P generation:

gametes: An → Achondroplasia dominant (A), No Achondroplasia recessive (n)

Heterozygousity describes the allelic makeup; these traits comprise two varying forms of a  gene. However, homozygous traits comprise identical forms of the gene.

Male: An  →  with Achondroplasia

Female: nn → without Achondroplasia

genotypes and phenotypes for parent and offspring...

Assuming heterozygousity of the male , for the cross

P generation:                         An × nn

                          Achondroplasia   × No Achondroplasia

F1 generation:

genotype:                      An × nn       ...(from punnet square)

phenotype:          2 with Achondroplasia ; 2 without

∴ 50% are genotypically heterozygous while 50% is homozygous , 2 with Achondroplasia ; 2 without

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