Monday, September 28, 2009

Multiple Alleles (Short Note)

A gene for a trait having three or more allelic forms are called multiple alleles. A well known example of multiple alleles in human beings is that of blood groups. The type of blood group that a person may have, depends upon the presence or absence of certain specific substances in the red blood cells. These substances are antigens and are of two kinds Antigen A and Antigen B. A person with Antigen A has blood group A and that with antigen B, has blood group B. A person with A and B antigens has blood group AB. Similarly a person lacking both antigens falls in blood group O. It is now known that there are three alleles responsible for this trait Gene 1A and 1B are responsible for the synthesis of antigens A and B respectively. Their alternative genes (i) synthesize no antigens at all. As only two alleles can occur in the individual, therefore, three alleles can have only four possible combinations. Alleles 1A and 1B are co dominant and both are dominant over allele ‘i’ Blood groups are helpful in determining the paternity.

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1 Responses to “Multiple Alleles (Short Note)”

Anonymous said...
January 30, 2012 at 6:53 AM

keep it up!


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