Question

Which type of allele often leads to a decrease in the production of a functional protein?

1) Dominant allele
2) Recessive allele
3) Homozygous allele
4) Heterozygous allele

Answer 1

The type of allele that often leads to a decrease in functional protein production is the recessive allele, which usually results in a nonfunctional protein or no protein.

Step-by-step explanation:

An allele is a variant form of a gene, and the type that typically leads to a decrease in the production of a functional protein is the recessive allele. Recessive alleles often contain mutations that result in a nonfunctional protein or no protein product at all. They only affect the phenotype when present in two copies, that is, in a homozygous state. However, if a dominant allele is present, its effect typically masks the recessive allele's effect. For instance, if a plant is homozygous for tallness (TT) and greenness (GG), its genotype is TTGG, and its phenotype is a tall, green plant.

Dominant alleles, on the other hand, can still result in phenotypic expression even when only one copy is present because they typically encode for a functional protein. This is why the phenotypes associated with dominant alleles can be seen in both homozygous dominant (AA) and heterozygous (Aa) genotypes. A notable exception is the case of dominant negative mutations or antimorphic mutations, which can adversely affect the function of the wild-type protein.