Question

Now, suppose that the three tomato genes from Part A did not assort independently, but instead were linked to one another on the same chromosome. Would you expect the phenotypic ratio in the offspring to change? If so, how?Which statement best predicts the results of the cross MmDdPp x mmddpp assuming that all three genes are linked?a. Lack of independent assortment means that you cannot predict the frequencies of phenotypes in the offspring.b. All eight possible phenotypes would occur in equal numbers in the offspring (1:1:1:1:1:1:1:1).c. All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes.d. Only the parental phenotypes could possibly occur in the offspring.

Answer 1

Answer:

c. All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes

Explanation:

When genes are linked they do not assort independently. Instead, the alleles on the parental chromosome will have a tendency to migrate together to the same pole of the cell. To produce gametes with genotypes different than the parentals crossing over must happen between the genes of homologous chromosomes during meiosis. However, recombination is a rare event, so the recombinant gametes will be less frequent than the parentals (those that arise when no recombination occurs between genes) and for that reason a greater proportion of the offspring will have parental phenotypes.