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प्रश्न
Write a note on multiple alleles considering examples of human blood groups.
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उत्तर
- More than two alternative forms (alleles) of a gene in a population occupying the same locus on a chromosome or its homologue are known as multiple alleles.
- ABO blood group system in humans is an example of multiple allelism because gene I exists in three allelic forms IA, IB and IO.
- Here, allele IA codes for type A blood, allele IB codes for type B blood and allele IO codes for type O blood.
- Allele IO is recessive to the alleles IA and IB.
- Thus, with these three alleles, we can have 6 different genotypes and 4 different phenotypes for blood groups.
| Genotype | Phenotype (Blood group) | |
| 1. | IA IA or IA IO | Type A |
| 2. | IB IB or IB IO | Type B |
| 3. | IA IB | Type AB |
| 4. | IO IO | Type O |
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संबंधित प्रश्न
Which one of the following is a true pleiotropic gene?
The genotypes of a husband and wife are IAIB and IAi respectively. How many different genotypes and phenotypes are possible among the blood types of their children?
______ is an example of pleiotropy.
______ represents the genotype of a carrier carrying a gene for sickle-cell anaemia.
The number of phenotypic and genotypic individuals produced during a typical Mendelian monohybrid cross will be ______ and ______ respectively.
Which one of the following statements is correct?
A gene which causes death of its bearer is ______.
ABO blood group system can be explained by ______.
______ occurs when heterozygotes express both homozygous phenotypes equally.
Give a cross for incomplete dominance using a suitable example.
