Sat December 29, 2012 By:

plz make me understand the blood groups of humans,ie which is dominant n which are recesssive briefly.

Expert Reply
Mon December 31, 2012

 There are 4 blood groups in humans – A, B, AB and O.

The blood group antigens are controlled by an autosomal gene designated I (isohaemaglutinin) which has 3 alleles IA, IB and IO. Allele IA is dominant over the allele IO and allele IB is dominant over IO .



Blood group                     Allele

A                               IAIA or IAIO      

B                               IBIB or IBIO

AB                             IAIB

O                              IOIO


In addition, the blood groups may be Rh +ve or Rh-ve, depending on the presence or absence of Rh factor in blood.

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