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?

Answer 1

All eight phenotypes are possible but parental phenotypes will be more in number

Step-by-step explanation:

In the cross MmDdPp X mmddpp eight types of offspring are possible because MmDdPp will produce eight types of gametes. These offspring are:

• MDP/mdp
• Mdp/mdp
• mDp/mdp
• mdP/mdp
• MDp/mdp
• mDP/mdp
• MdP/mdp
• mdp/mdd

In absence of linkage, the genes would have assorted independently producing all the eight types of offspring in equal number. Hence the phenotype ratio would be 1:1:1:1:1:1:1:1.

If the genes are linked they will show the tendency to get inherited together and crossing over will not take place up to the expected degree. Hence fewer recombinants will be produced and more parental type offspring will be produced.