Short Answer TypeWhat are 'true breeding lines' that are used to study inheritance pattern of traits in plants?
Name any two types of cells that act as 'cellular barriers' to provide innate immunity in humans.
Identify 'a' and 'b' in the figure given below representing proportionate number of major vertebrate taxa.
Why do algae and fungi shift to sexual mode of reproduction just before the onset of adverse conditions?
How does the gene 'I' control ABO blood groups in humans? Write the effect the gene has on the structure of red blood cells.
In humans, the ABO blood groups are controlled by a gene called gene I. It has three alleles, namely IA, IB and i. Two of the three alleles IA and I B dominate over i. But IA and I B express themselves in each other’s presence and hence are co-dominant.
Showing the Genetic Basis of Blood Groups in Human Population is given as follows:
|
Allele from Parent 1 |
Allele from Parent 2 |
Genotype of offspring |
Blood type of offspring |
|
I A |
I A |
I A I A |
A |
|
I A |
I B |
I A I B |
AB |
|
I A |
i |
I A i |
A |
|
I B |
I A |
I A I B |
AB |
|
I B |
I B |
I B I B |
B |
|
I B |
i |
I B i |
B |
|
i |
i |
i i |
O |
These alleles help to determine the structure of the red blood cells. The plasma membrane of red blood cells has sugar polymers that protrude out from its surface and the kind of sugar is regulated by the gene 'I' of ABO blood group. The alleles IA and IB produce A and B types of sugar, while allele i does not produce any sugar. Thus when allele ‘IA and IA’ and ‘I A and i‘ are present together then the red blood cells have sugar A on the surface. When IB and I B or IA and i are present then sugar B is found on the surface. When IA and I B are present both A and B sugar are found on the cell surface. While blood group O does not bear any sugar.
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