Two genes, A/a andB/b, control fruit color in squash. Theinheritance pattern for this trait fits one of the multiple genetypes that we discussed in class. A homozygous plant with whitefruit was crossed with a homozygous plant with yellow fruit. Allthe progeny had red fruit. When two F1 plants were crossed, the F2consisted of 38 white, 27 yellow, and 89 red.
(a) (2 pts) Which type of geneinteraction do we see here? Explain your reasoning.
(b) (2 pts) What is the expected ratioof white to yellow to red fruit in the F2?
(c) (3 pts) What were the genotypes ofthe P generation plants?
(d) (5 pts) Test your hypothesizedgene interaction model with Chi-square analysis. Please include allthe components of Chi-square analysis in your answer.
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(e) (5 pts) The diagram explains howthe two genes interact at the molecular level. Compounds X, Y, andZ determine fruit color depending on which of the two chemicalreactions occur. Each gene produces an enzyme that is either activeor inactive depending on its genotype.
When an enzyme is active, the reactionit catalyzes occurs; when it is inactive, the reaction is blocked.Write in the boxes the genotypes that would explain the inheritancepattern.
(2 pts) Please fill in the box withthe according genotypes.
(3 pts) Interpret the pathway withyour own words (e.x. how to read this pathway? how you get white,yellow and red colors from different genotypes by following thispathway graph? Circle out the epistatic genotype in yourpathway)
