Question

Which type of inheritance is characterized by distinct expression of the gene products of both alleles?

1) Incomplete dominance
2) Codominance
3) Polygenic inheritance
4) Epistasis

Answer 1

Codominance is the type of inheritance characterized by the distinct expression of the gene products of both alleles.

Step-by-step explanation:

Codominance is the type of inheritance that is characterized by the distinct expression of the gene products of both alleles. In codominance, both alleles for the same characteristic are simultaneously expressed in the heterozygote.

For example, the MN blood groups of humans are an example of codominance. The M and N alleles are expressed as M or N antigens on the surface of red blood cells. Homozygotes (LMLM and LNLN) express either the M or N allele, while heterozygotes (LMLN) express both alleles equally.

In a self-cross between heterozygotes expressing a codominant trait, the three possible offspring genotype are phenotypically distinct. However, the 1:2:1 genotypic ratio characteristic of a Mendelian monohybrid cross still applies.