The amount of enzyme activity in a cell that is homozygous for a mutant allele is 0 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 0 units. What type of allele is the mutant allele?
A)null
B)hypomorphic
C)hypermorphic
D)dominant negative
E)neomorphic

Question

Quizplus · Accepted Answer

The fact that the heterozygote exhibits 0 units of enzyme activity points to a dominant negative allele, where the mutant protein product interferes with the function of the wild-type protein. The mutant allele is not null (choice A) as it produces a non-functioning protein, and not hypomorphic (choice B) as it produces no enzyme activity at all. It is not hypermorphic (choice C) as it does not produce more enzyme activity than the wild-type allele. It is also not neomorphic (choice E) as it does not produce a novel enzyme activity.

The Amount of Enzyme Activity in a Cell That Is