Inheritance pattern of ABO blood groups in humans show dominance , co - dominance and multiple allelism. Explain each concept with the help of blood group genotypes.

Inheritance pattern of ABO blood groups in humans show dominance , codominance and multiple allelism can be explained as

  • In dominance, F1 progeny resembles one of the parent. 
  • In co-dominance, the F1 progeny resembles both the parents
  • Multiple alleles: When more than two alleles control a character, as in human blood groups
  • Example: ABO blood groups in human beings
  • ABO blood groups are controlled by gene I. Gene I has three alleles, AB and i. A person possesses any two of the three alleles.
  • IA and B dominate over i. But with each other, IA and IB are co-dominant.
  • IA and B contain A and B types of sugar, while i does not contain any sugar.

     

    Allele from Parent 1

    Allele from Parent 2

    Genotype of offspring

    Blood type of offspring

    A

    A

    A I A

    A

    A

    B

    A I B

    AB

    A

    i

    A i

    A

    B

    A

    A I B

    AB

    B

    B

    B I B

    B

    B

    i

    B i

    B

    i

    i

    i i

    O

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