1) (6 point question) A breeder had two different pure breeding lines of cantalo
ID: 274324 • Letter: 1
Question
1) (6 point question) A breeder had two different pure breeding lines of cantaloupe; one with a white fruit the other with a yellow fruit. He crosses these two together and produces a hybrid that has white fruit. When he selfs the hybrid he finds that the progeny have either white, green or yellow fruit. The ratio of the progeny fruit color he observes is 12 white : 1 yellow : 3 green fruit.
A) (3 points) A biochemist is interested in determining the pathway for pigmentation in cantaloupe. He hypothesizes potential biochemical pathways based on the 12:3:1 ratio seen by the breeder (there are others). Determine the expected phenotypes of the progeny based on the pathway shown. Then describe any epistatic interactions you see between the genes. (see a list of assumption below the table)
• Assume that the hypothesized C enzyme is wildtype (CC) in both pure bred lines.
• Enzyme A acts by inhibiting the first step of the pathway in each case.
B) (1 point) Can the biochemist rule out any of the pathways above based on the information he has from the breeder? Briefly explain your reasoning.
C) (2 points) What biochemical test could be done to narrow down the pathway to one of the three above.
Proposed pathway Expected phenotvpes in :a dihybrid cross Epistatic interaction Green Abb= - 1Colorless -- Colorless Yellow Abb = Green Yellow aabb= Colorless A bb = aabb = Colorless Yellow GreenExplanation / Answer
1. A_B_ white
A_bb white
aaB_ green
aabb yellow
2. A_B_ white
A_bb white
aaB_ yellow
aabb green
3. A_B_ white
A_bb white
aaB_ green
aabb yellow
the epistatic interaction is dominant epistasis in all the cases.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.