chapter 3 section 7

Question 1

What is the structure of ATP?

Answer 1

ATP consists of adenine + ribose + triphosphate chain.

Question 2

What is special about the triphosphate chain?

Answer 2

It contains two pyrophosphate linkages, which release large amounts of energy upon hydrolysis.

Question 3

Where are the high-energy bonds in ATP?

Answer 3

Between the phosphate groups (highlighted in yellow).

Question 4

What is the role of the ribose?

Answer 4

Connects adenine to the triphosphate chain via a methylene group.

Question 5

Which part of ATP carries the dissociable protons?

Answer 5

The hydroxyl groups of the triphosphate chain.

Question 6

What does a positive ΔG°′ (+13.8 kJ/mol) indicate for the reaction A ⇌ B?

Answer 6

The reaction is thermodynamically unfavorable, with very little product formed at equilibrium (K_eq = 0.0038).

Question 7

What happens when the reaction A ⇌ B is coupled to ATP hydrolysis?

Answer 7

The overall ΔG°′ becomes negative (-16.7 kJ/mol), making the reaction spontaneous.

Question 8

Does the multiplication factor from ATP coupling depend on the specific reaction or ΔG°′ of A ⇌ B?

Answer 8

No, it mainly depends on the concentrations of ATP, ADP, and Pi.

Question 9

What is the significance of coupling in biochemical reactions?

Answer 9

Reactions with positive ΔG can proceed when coupled to reactions with large negative ΔG.

Question 10

Why are coupled reactions important in living systems?

Answer 10

They allow thermodynamically unfavorable reactions (ΔG > 0) to proceed by pairing them with highly favorable reactions (ΔG < 0).

Question 11

How can we predict if coupled reactions will proceed spontaneously?

Answer 11

By summing the ΔG values of each reaction; if the total ΔG is negative, the overall process is spontaneous.