What do you mean by Genotype and Phenotype ? How to calculate its percentage?

Asked by  | 15th Mar, 2013, 09:56: AM

Expert Answer:

Genotype is the genetic constitution of an individual organism. Phenotype is the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

 

In a dihybrid cross, the phenotypic ratio is 9:3:3:1 whereas the genotypic ratio is 1:2:1:2:4:2:1:2:1.

For example - In a cross between RRYY (round yellow seeds of pea plant) and rryy (green wrinkled seeds of pea plant), all F1 offspring would be RrYy i.e. Round yellow.

In F2 generation, we will get the following combination of gametes - RY Ry rY ry RY. When crossed, they would give the following possible offspring:

1 YYRR + 2 YYRr + 1 YYrr + 2YyRR + 4YyRr + 2 yyRR + 1yyRR + 2yyRr + 1yyrr

Thus the genotype ratio is 1:2:1:2:4:2:1:2:1

 

The phenotype ratio is 9:3:3:1.  i.e. 9 round-yellow : 3 wrinkled-yellow : 3 round-green : 1 wrinkled-green pea seeds

Answered by  | 16th Mar, 2013, 08:46: AM

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