Gene A converts compound A green to compound B blue Gene B c

Gene A converts compound A (green) to compound B (blue). Gene B converts compound B to compound C (red). These compounds determine the color of the individual. In a self cross of AaBb individuals, what proportion of blue to green offspring should be seen?

Solution

Among these three, compounds A is lethal to organism. It has to convert to blue or red. Compound A(green) is converted to compound B(blue) by gene A. So a function gene with AA, or AA is required. genotype with aa is lethal to organism.

SELF CROSS:

Parents AaBb X AaBb

Gamets AB Ab aB ab AB Ab aB ab

male/

female

1. From the the above progeny aaBB, aaBb and aabb are dead organism, becuase they lack function gene A

2. AABB, AABb, AaBB and AaBb these organisms contain functional copy of Gene B and will convert compount B(Blue) into compound C (red).

3. AAbb and Aabb these organisms contain functional copy of Gene A and will convert compound A(green) into compoind B(blue).

4. From the above observation there are 9 organisms that are Red (able to convert blue to red)

3 organisms that are Blue (able to convert green to blue)