Two genes, A and B, are linked. An individual of genotype A b / A b is crossed t
ID: 265145 • Letter: T
Question
Two genes, A and B, are linked. An individual of genotype A b / A b is crossed to one that is a B / a B. The F1 is selfed and an F2 is obtained. Which of the following ratios most likely represents the phenotypic ratio observed in this F2?
Why is it 51:24:24:1
Two genes, A and B, are linked. An individual of genotype A b / A b is crossed to one that is a B / a B. The F1 is selfed and an F2 is obtained. Which of the following ratios most likely represents the phenotypic ratio observed in this F2?
Why is it 51:24:24:1
Explanation / Answer
Parental genotypes = AbAb and aBaB
Therefore, F1 genotypes will be = AaBb
Since, it is given in the question that A and B genes are linked which means that they will be inherited together. Therefore, instead of obtaining the normal mendelian ratio of 9:3:3:1 in F2 generation, we will have a completely different ratio. Actually, since genes A and B are linked together, it will behave as a monohybrid cross.
The Punnet square for the cross is given as follows:
AaBb x AaBb F1 generation
AB ab AB ab Gametes
Thus, the phenotypic ratio will be 1:2:1
The ratio 51:24:24:1 signifies that the individuals with linked genes A and B are 51, the individuals with parental genotypes are 24 each and the the individual with a recombinant phenotype resulting from crossing-over is 1.
Gametes AB ab AB AABB AaBb ab AaBb aabbRelated Questions
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