DD - Glycolysis

Question 1

Why is not all the Gibbs energy released as heat? (3)

Answer 1

1. Biological systems cannot utilise heat as a source of energy
2. No single reaction of metabolism requires this amount of energy to be released in one step
3. Always need to overcome the activation energy. Enzymes are capable of effecting only small changes when they catalyse biological reactions, releasing the energy in steps

Question 2

What occurs in glycolysis?

Answer 2

Glucose –> 2 x Pyruvate
2 ATP
2 NADH + 2H+

Question 3

What coenzymes are involved in glycolysis?

Answer 3

ATP/ADP - release/accept phosphate groups
NADH/NAD+ - release/accept protons from substrates

Question 4

What is the structure of glyccerol?

Answer 4

3 carbon backbone with 3 hydroxyl groups

Question 5

What is the structure of acetone?

Answer 5

A ketone with 2 methyls

Question 6

What does GAP stand for?

Answer 6

Glyceraldehyde-3-phosphate

Question 7

What occurs in the first 5 steps of glycolysis? (Energy Investment)

Answer 7

1. Glucose –> Glucose-6-Phosphate (Phosphate added)
2. Glucose-6-Phosphate –> Fructose-6-Phosphate (C2 Carboxylated)
3. Fructose-6-Phosphate – > Fructose-1,6-Bisphosphate (Phosphate added)
4. Fructose-1,6-Bisphosphate –> DHAP + GAP (Cut in half)
5. DHAP –> GAP (Phosphoester rearranged)

Question 8

What are the last 5 steps of glycolysis? (Energy Payoff)

Answer 8

6. GAP –> 1,3-bisphosphoglycerate (Carboxyl phosphorylated)
7. 1,3-bisphosphoglycerate –> 3-phosphoglycerate (Phosphate lost)
8. 3-phosphoglycerate –> 2-phosphoglycerate (Phosphoester rearranged)
9. 2-phosphoglycerate –> Phosphoenolpyruvate (H2O removed)
10. Phosphoenolpyruvate –> Pyruvate (Phosphate lost)