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BMS 201 2018 Exam II A) Positive Feedback B) Negative Feedback 12) Pictured abov

ID: 252424 • Letter: B

Question


BMS 201 2018 Exam II A) Positive Feedback B) Negative Feedback 12) Pictured above are two biosynthetic pathways showing six metabolites (A-B, X-Z). 12 points A) In the positive feedback loop metabolite C affects the enzyme that converts B to C. How metabolites in the biosynthetic pathway? Provide the specific letters and how levels change. 8) in the negative feedback loop metabolite Z affects the enzyme that converts A to B. How does this affect the levels of metabolites in the biosynthetic pathway? Provide the specific letters and how levels change.

Explanation / Answer

A) In positive feedback, C inhibits only the conversion of B to C and only B is required for the synthesis of X, Y and Z. So only the synthesis of C is inhibited which leads to increased B. So the Synthesis of X, Y and Z from B is also increased. Overall, the levels of C is kept constant and the levels of X, Y and Z is increased with Z being maximum.

B) In negative feedback, the Z metabolite inhibits the conversion of A to B. So the synthesis of all the metabolites produced from B including C, X, Y and Z are inhibited leading to a constant concentration of C, X, Y and Z.