BLOOD GROUP INHERITANCE

             K. Landsteiner and  his students discovered blood groups in human beings (1900-1902) known as ABO blood groups. A person's  is blood is classified into one of the four types: A, B, AB or O on the bassis of carbohydrate molecules present on the surface of red blood cells (which serve as antigens),

 i.e., if RBCs have carbohydrate

'A' on its surface, then the blood group is type 'A', if

'B', then it's type 'B'

and if both are present, then its type 'AB'

and when none are present, it is type 'O'

          The different blod groups can be  identified by testing these antigens with different anti-sera which result in clumping of blood cells, known as agglutination. If anti-sera match with their corresponding antigen, it results in agglutination.

           These blood groups determined by three alleles of a single gene: Iᴬ, Iᴮ and Iᴼ ( an example of multiple alleles). the genes Iᴬ,  and Iᴮ are dominant but show no dominance over each other, i.e., they are co-dominant whereas both genes, i.e., Iᴬ and Iᴮ are dominant over the gene Iᴼ  or 'i' therefore gene Iᴼ  or 'i' is recessive.