Chapter 7.7: Regulation of Aerobic Respiration

Question 1

What is the main control point in the oxidation of pyruvate?

Answer 1

o The main control point in the oxidation of pyruvate occurs at the committing step in the Krebs cycle with the enzyme pyruvate dehydrogenase, which converts pyruvate to acetyl-CoA

Question 2

How is the enzyme pyruvate dehydrogenase controlled in the oxidation of pyruvate?

Answer 2

 This enzyme is inhibited by high levels of NADH

Question 3

What is the control of glucose catabolism in glycolysis?

Answer 3

o The control point in glycolysis is the enzyme phosphofructokinase, which catalyzes the conversion of fructose phosphate to fructose biphosphate

Question 4

How is the enzyme phosphofructokinase controlled in glycolysis?

Answer 4

 ATP is an allosteric inhibitor of phosphofructokinase as is the Krebs cycle intermediate citrate
 High levels of both ATP and citrate inhibit phosphofructokinase

Question 5

How is the enzyme citrate synthetase controlled in the Krebs cycle?

Answer 5

o Another control point in the Krebs cycle is the enzyme citrate synthetase, which catalyzes the conversion of oxaloacetate and acetyl-CoA into citrate
 High levels of ATP inhibit citrate synthetase slowing down the entire catabolic pathway