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Describe the mechanism of inheritance of the ABO system of blood group, highlighting the principle of genetics involved in it. OR Explain the genetic basis of blood grouping in human population. |
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Answer» ▪ The alleles which are able to express themselves independently, even when present together are called co-dominant alleles and this biological phenomenon is called codominance.For example, ABO blood grouping in humans. • ABO blood groups are controlled by gene I. Gene I has three alleles IA, IB and IO/i. • IA and IB produce RBC surface antigens sugar polymer A and B, respectively, whereas i does not produce any antigen. • IA and IB are dominant over i hence IA and IB are dominant alleles and i is recessive allele as in IAi and IBi. • When IA and IB are present together, both express equally and produce the surface antigens A and B, hence show co-dominance. • Since humans are diploid, each person possesses any two of the three ‘I’ gene alleles, resulting into six different genotaypic combinations and four phenotypic Expressions. Table showing the genetic basis of blood groups in human population
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