Characteristics of Multiple Alleles

Multiple Alleles:

Multiple Alleles are defined as genes that are members of the same gene pair and are located on the same locus. All of them control the same character but each of the alleles affects that character somewhat differently than the others.

Explanation of Multiple Alleles:

In any diploid organism, a particular gene pair is represented by two alleles of the series, one allele on each of the two chromosomes of a homologous pair. This is because an organism has just two chromosomes of each type. These form a homologous pair. However, in the individuals of a population or species, many alternative forms of the same gene may be present. The grouping of all the possible alleles of a gene pair is defined as a system of multiple alleles and their mode of inheritance is called multiple allelism. The multiple allele system can be represented as A1, A2, A3, A4, …

Characteristics of Multiple Alleles:

1. Multiple alleles occupy the same locus within the homologous chromosomes. It means that only one other member of the series is present in a given chromosome.

2. Since only two chromosomes of each type are present in each diploid cell, only two genes of the multiple series are found in a cell and also in a given individual.

3. The gametes contain only one chromosome of each type, therefore, only one allele of the multiple series in each gamete.

4. Crossing over doesn’t occur in the multiple alleles.

5. Multiple alleles control the same character, but each of them is characterized by different manifestations. Sturtevant has summarized that they carry the same functions but with varying degree of efficiency.

6. The multiple alleles of a series are more often related as dminant and recessive. More commonly, the normal gene is dominant to all other mutant alleles. Even the intermediate members of the series may be related as dominant and recessive or they may exhibit codominance. Therefore, multiple alleles act in some way to control the various steps in a chemical reaction.