Question

explain why a recessive allele is unable to express itself in a heterozygous state?

Answer 1

In a diploid organism, there are two copies of each gene, i.e., pair of alleles. These two alleles are not always identical, as in a heterozygote. One of them may be modified due to mutation. The unmodified functional allele that represents the original phenotype behaves as dominant allele and codes for functional protein. The mutated nonfunctional allele behaves as recessive allele and codes for mutant or non functional protein. The phenotype of the organism will only be dependent on the functioning of the unmodified allele. Hence, in a heterozygote, the dominant allele will express itself whereas recessive allele will remain hidden.