Suppose that we are working with a diploid plant species that normally is able t

Question

Suppose that we are working with a diploid plant species that normally is able to produce product E from metabolite A through four enzyme-catalyzed biochemical steps, as diagrammed below. We have three strains (m1, m2, and m3) that each have a single recessive mutation that prevents production of E (these strains show the mutant phenotype). When we cross m1 x m2, the plants have the wild type phenotype, but when we cross m1 x m3, the offspring cannot make E.

A) We find that strain m1 accumulates metabolite C. What enzyme is defective in this strain (1/3 credit)?

B) What enzyme(s) could be defective in strains m2 and m3, based on the cross results (1/3 credit)?

C) Is it possible that all three mutant strains would be able to produce product E if they were provided with metabolite D in their growth medium? Briefly explain your answer (1/3 credit)?

(1/3 credit)? e rposible thatall hree mutant strains C) Is it possible that all three mutant strains wou were provided with metabolite D in their growth (1/3 credit)? Enzymes Metabolite A B C D E 7 (WILL BE GRADED) The following short pe

Explanation / Answer

A) Enzyme-3 would be defective in the m1 strain that leads to accumulation of Metabolite-C

B) In case of m2, I am sure about the defect in any enzyme, may be it (alleles that coding for genes of above enzymes) stands in heterozygous condition. That could not be expressive as a phenotypic character. But in m3 any of enzymes (E1, E2, E3 and E4) could be defective.

C) M1 strain can able to form metabolite E if it is provided by D in the growth medium. Since m1 is defective with E3 but can't assure in case of E4. So E4 might be active in m1 strain that can convert the D into E.

It seems that m2 can also produce metabolite-E, since m1 x m2 cross did not affect the phenotype of progeny that suggests it capability in producing metabolite-E due to active E4.

In case of m3, it is doubtful to produce E, since m1 x m3 cross could not produce wild-type progeny that suggesting a defect in E4.   

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.