pyruvate oxidation + tca cycle

Question 1

overview of catabolism (3)

Answer 1

1. digestion of large molecules in food to smaller molecules
2. breakdown of the smaller molucules to acetyl CoA
3. comprises the TCA cycle and oxidative phosphorylation

Question 2

outline the net process of pyruvate oxidation

Answer 2

pyruvate + CoA + NAD+
->
acteyl CoA + CO2 + NADH + H+

• pyruvate dehydrogenase (PDH) catalyses pyruvate (3C) to acetyl CoA (2C)

Question 3

where does pyruvate oxidation occur

Answer 3

mitochondrial matrix

Question 4

identify pyruvate dehydrogenase cofactors (5)

Answer 4

1. CoA
2. NAD+
3. FAD
4. lipoamide
5. TPP

Question 5

what is role of TCA cycle

Answer 5

• central pathway that facilitates the recovery of energy from metabolic fuel
• produces reduced co-factors that drives ATP synthesis

Question 6

outline net reaction of TCA cycle

Answer 6

acetyl-CoA + 3 NAD+ + FAD + GDP + Pi + 2 H2O
->
2 CO2 + 3 NADH + FADH2 + GTP + 3H+ + CoA

Question 7

what is oxidised and reduced in TCA cycle

what are 2 main products

Answer 7

oxidised:
acetyl-CoA

reduced:
3 NAD+ -> 3 NADH
FAD -> FADH2

products:
2 CO2
ATP

Question 8

what are the 3 levels of regulation in TCA cycle

what are the inhibitors and stimulator

Answer 8

TCA regulated by ATP & NADH concentrations

• ATP & NADH = inhibitors
• ADP = stimulator

1. pyruvate dehydrogenase switched off when ATP conc high
2. isocitrate dehydrogenase stimulated by ADP
3. alpha-k dehydrogenase inhibited by ATP, NADH and succinyl CoA