18. Bioenergetics

Question 1

What is the control point in the link reaction?

Answer 1

Pyruvate dehydrogenase
conversion of pyruvate > acetyl CoA

If energy levels are high, pyruvate dehydrogenase is phosphorylated, becoming inactive.
Re-activation is signalled by Ca2+

Question 2

Acetyl CoA cannot be converted back to glucose.

True or False?

Answer 2

TRUE

Question 3

How many protons are required to cross the inner membrane space to synthesise 1 molecule of ATP?

Answer 3

4 H+

3 to drive ATP synthase
1 to transport a phosphate into the matrix (proton exchanged)

Question 4

NADH cannot cross the inner membrane.

True or False?

Answer 4

TRUE

Question 5

Electron transport + ATP synthesis are tightly coupled, if either stops working, electron transport stops.
How can this issue be resolved?

Answer 5

Uncouplers (weak acids)
They dissipate the proton gradient so electron transport can continue without ATP.
Heat is generated instead.