Difference Between Dominant and Recessive Alleles

Dominant vs Recessive Alleles

Inheritance is one of the most important principles in the life. Meiosis governs the inheritance of living organisms.  Paring of homologous chromosomes occurs during the process of meiosis. Usually a chromosome contains a number of genes, and they exist in specific places. If genes exist in the same location, in the homologous chromosomes, they are said to have the same locus. As they are located in the same loci, in maternal and paternal chromosome, these genes have the same trait. In such a situation, the two genes are called alleles. Alleles can be dominant or recessive. A dominant allele is always expressed while the recessive allele is expressed when only dominant allele is absent. If two alleles present in the organism that are identical, then it is called “Homozygous”, while if two alleles are different, and then called “Heterozygous”. Actually the dominance and recessivity are phenotypic correlation of two alleles.

Dominant Allele

From the two genes in the same loci of maternal and paternal chromosome, the dominant allele is the stronger one. This dominant allele is expressed phenotypically in the case of heterozygous and homozygous.

For an example, if we consider the dominant allele as (A) and recessive allele as (a), then in the case of homozygous, the two alleles can be written as AA, and it can be written as Aa, in the case of heterozygous. In both situations, the dominant allele can express its phenotype over recessive allele.

Recessive Allele

From the two alleles, the weaker one is known as recessive allele. This recessive allele is expressed only in the case of homozygous. In the case of heterozygous, the dominant allele masks the phenotype of the recessive allele.

For an instance, if we consider the dominant allele as (A) and recessive allele as (a), the recessive allele can express its phenotype only in the case of ‘aa’. It is not expressed in its Aa state due to the effect of the dominant allele.

What is the difference between Dominant and Recessive Alleles?

• Dominant allele is the stronger one from the two alleles and the weaker one is the recessive allele.

• A dominant allele can express its phenotype in its both heterozygous and homozygous states, but the recessive allele expressed its phenotype only in its homozygous state or when dominant allele is absent.