Define codominant and multiple alleles and explain how they

Define codominant and multiple alleles and explain how they are related to A, B, O blood type inheritance.

Solution

a) Codominant alleles-When the alleles shows codominant it means that the alleles are not dominant and both are expressed in the phenotype of heterozygote.

b) Multiple alleles-If there are four or multiple number of phenotypes are possible for a particular trait then more than two alleles for that trait must be exist in the population and it is called multiple alleles.

The relationship of codominant and multiple alleles with A, B, O blood type inheritance are as follows - :

ABO system is due to the gene that codes for molecules present at the surface of red blood cells. There are four possible phenotype A, B, AB, O for the blood type. There are three alleles that determine the blood type which defines the concept of multiple alleles. Also out of three alleles O is recessive to the alleles of A and B which is represented by the letter \'i\'.

Here a child can receive blood group type from both the parents.

I^A I^A -Type A

I^A i - Type A

I^B I^B   -Type B

I^B i - Type B

I^A I^{B _}Type AB

ii - Type O

The alleles I^A and I^B are codominant alleles as it is present in the form of I^A I^B where i is recessive. The blood type A and B can either be homozygous I^A I^A or I^B I^B or heterozygous I^A i or I^B i for a particular trait.