Multiple Allelism

• Mendel proposed that each gene has two contrasting forms i.e, Alleles. But there are some genes which are having more than two alternative forms.
• Presence of more than two alleles for a gene is known as multiple allelism and each are able to express itself.
• Example – Different types of red blood cells that determine ABO blood grouping in human beings ABO blood grouping in human beings. ABO Bloods groups are controlling by gene I.

CO-DOMINANCE

In co dominance both the alleles of heterozygous condition are able to express itself independently.
There is no dominant and recessive relation ship between both the allele in heterozygous condition.
Example:- AB Blood group in human being both express their own types of sugars, this is known as co- dominance. where both the allele IA, IB is able to express itself independently.