(Dr. McLachlin) (Unit B) Topic Note 10

Question 1

Activation/Deactivation:

Pyruvate Dehydrogenase

Answer 1

• Activated: Dephosphorylated
• Inactive: Phosphorylated

Question 2

What is pyruvate dehydrogenase phosphorylation/dephosphorylation promoted by?

(Explain why for each answer)

Answer 2

Phosphorylation (Inactive)
* Acetyl-CoA
* NADH

Dephosphorylation (Active)
* Pyruvate
* Insulin

• Acetyl CoA: A product, thus too much will inhibit activation
• NADH: A product, thus too much will inhibit activation
• Pyruvate: A reactant, thus too much will activate
• Insulin: High insulin levels indicates there is a lot of glucose, thus pyruvate will be plenty, causing activation

Question 3

Are reactions of the Citric Acid Cycle reversible?

Answer 3

No, the Citric Acid Cycle is unidirectional