Explain the Terms with Example - Co-dominance - Biology


Explain the terms with example - Co-dominance


Solution 1


Co-dominance is the phenomenon in which both the alleles of a contrasting character are expressed in heterozygous condition. Both the alleles of a gene are equally dominant. ABO blood group in human beings is an example of co-dominance. The blood group character is controlled by three sets of alleles, namely, IA, IB, and i. The alleles, IA and IB, are equally dominant and are said to be co­­-dominant as they are expressed in AB blood group. Both these alleles do not interfere with the expression of each other and produce their respective antigens. Hence, AB blood group is an example of co-dominance

Solution 2

Codominance : Codominance is the phenomenon of two contrasting alleles of the same gene lacking dominant recessive ratio and expressing themselves simultaneously when present together. E.g. ABO blood group system – Human blood group AB is formed when alleles of blood groups A and B are present together (IAIB). Such RBCs carry both antigen A & B showing that both die alleles are expressing their effect phenotypically & codominant

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Chapter 5: Principles of Inheritance and Variation - Exercises [Page 94]


NCERT Biology Class 12
Chapter 5 Principles of Inheritance and Variation
Exercises | Q 13.1 | Page 94

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