Question

Part 1 - Mendelian Genetics Review

Match the example with the type of inheritance.

A) Complete dominance B) Incomplete dominance C) Codominance

_______Pea shape in garden pea plants: The W gene encodes for an enzyme that synthesizes starch granules in peas. The w gene encodes for a dysfunctional enzyme that will not synthesize the starch granules. The presence of starch granules makes the seeds round, and the absence of the starch granules results in wrinkled seeds. Heterozygotes have only half as many starch granules, yet that is enough to make the seeds round.

_______Piebald (white) spotting in cats: Cats homozygous for the s allele do not have any white spots. Cats with the S allele are completely white. Cats that are heterozygous (Ss) are about 50% white.

________ Sickle-cell anemia in humans: Heterozygotes have one copy of the wild-type hemoglobin and one copy of the mutant hemoglobin. Phenotypically, heterozygotes have about half the number of sickled red blood cells as
homozygotes do.

Answer 1

Complete dominance : this is an example of complete dominance because the phenotype of the dominant allele is expressed here in the heterozygous condition. Pea shape in garden pea plants: The W gene encodes for an enzyme that synthesizes starch granules in peas. The w gene encodes for a dysfunctional enzyme that will not synthesize the starch granules. The presence of starch granules makes the seeds round, and the absence of the starch granules results in wrinkled seeds. Heterozygotes have only half as many starch granules, yet that is enough to make the seeds round.

Incomplete dominance: Piebald (white) spotting in cats: Cats homozygous for the s allele do not have any white spots. Cats with the S allele are completely white. Cats that are heterozygous (Ss) are about 50% white.

Co-dominance: This is co dominance codition because the trait both the allels are presnt in the offspring. Sickle-cell anemia in humans: Heterozygotes have one copy of the wild-type hemoglobin and one copy of the mutant hemoglobin. Phenotypically, heterozygotes have about half the number of sickled red blood cells as
homozygotes do.