Important Topic of Biology: Multiple Alleles

Alleles or allelomorphs are other types of genes present in the same area on homologous chromosomes. Some genes contain more than two types of allelic, called multiple alleles. A diploid cell contains any two alleles, each of which has a homologous chromosome and the haploid cell contains only one allele. When an element is dominated by many alleles it is called multiple allelism.

Multiple Alleles Definition

Gregor Mendel suggested that each gene contains only two alleles. Alleys are described as different genes that exist in two or more ways. Each gene is inherited from two alleles, that is, one for each parent. Therefore, this means that there will be two different alleles of the feature.

Breeds with different genetic collections are described as heterozygous and those with genotype species formed by the same alleles (i.e. genetics of a particular gene) are described as homozygous. Although humans (and all living things diploid) can have only two alleys in any given gene, many allele features may be present at the human level. Therefore, many alleles are important in promoting diversity between similar species.

In the Mendelian legacy, the chromosomal space provided was occupied by two different types of other genes – one controlling and one repetitive. These methods are two alleles of the same gene. However, forgiven people, there are cases where there are more than two alternatives (allele). Those conditions are called “multiple allelism” in which different genetic variants are present in humans. These three or more genetic variants are called multiple alleles.

Characteristics of Multiple Alleles

• Many gene alleles occupy the same space on the chromosome.
• Many alleles are one of the same genetic variants and therefore influence the same factor.
• The wild allele dominates most of the mutant alleys.
• The wild type is considered normal and all other alleles are considered diverse.
• A distinct or flexible allele may be strong, repetitive, or have a moderate phenotypic effect.
• Most alleles are present at the human level and a person may have only two alleles of a given gene.
• A person may have only one type of allele (homozygous) or two different alleles (heterozygous).
• A series of flexible alleles can be present in the community. They are produced by automatic conversion to wild-type and mutant alleles.
• Many alleles lead to the formation of various characteristic phenotypic traits in the population.

Examples of Multiple Alleles

The most common examples of many alleles are rabbit coat color, blood groups A, B, AB, and O people, and Drosophila eye color.

1. Blood Groups in People

Blood types A, B, AB, and O in humans are determined by three genes. The gene I, which determines blood type, exists in three allelic types, namely IA, IB, and i. Allele IA produces more antigen A in red blood cells and allele IB produces more B antigen B red blood cells and the allele means no antigen. Allele IA and IB are codominant over allele i.

A person has two of the three alleles in the homologous chromosomes. If a person has two IA (IAIA) or one IA and one allele (IAi) then the blood group is group A. Similarly, IBIB and IBI cause blood type B, IAIB produces blood type AB and the alleles (ii) cause blood type O.

2. The Color of the Coat Than the Rabbit

The color of the rabbit’s coat is determined by the C gene. The C gene contains many allelic species that lead to various phenotypes. Different types of coat color phenotypes for rabbits are agouti (full color), chinchilla, Himalayan, and albino.

The four most common alleles of the C gene are C, cch, ch, and c. Rabbits with genotype CC have black or brown fur, cchcch has a chinchilla or gray coat, chchs have a Himalayan pattern and cc has a white coat color, i.e. albino.

Because of the many alleles, there are many possible combinations of alleles.

• The black C allele dominates over the other three alleles.
• The cch (chinchilla) allele exhibits incomplete dominance over the Himalayan allele and albinos.
• The ch (Himalayan) allele indicates dominance over the albino allele (c).

3. Eye Color in Drosophila

Eye color in Drosophila is another attribute determined by many alleles. There are twelve different alleles showing the phenotype between wild red (w +) and white (w). Eg. coral, blood, eosin, cherry, apricot, etc. The red color of the wild species dominates over all other flexible alleles and the white color exceeds all alleles.