Aerobic Respiration Stage 3 - Krebs Cycle

What is the Krebs cycle also known as?

citric acid cycle

Where does the Krebs cycle occur?

mitochondrial matrix

What is stage 1 of the Krebs cycle?

converting acetyl coenzyme A into citrate

Outline stage 1 of the Krebs cycle as converting acetyl coenzyme A into citrate (5)

acetyl coenzyme A is a 2-carbon molecule, oxaloacetate is a 4-carbon molecule, acetyl coenzyme A and oxaloacetate react to form citrate, citrate is a 6-carbon molecule, at the same time this reaction is occurring coenzyme A is released to be reused in the prior stage of the link reaction

What is stage 2 of the Krebs cycle?

decarboxylation and dehydrogenation of citrate

Outline stage 2 of the Krebs cycle as decarboxylation and dehydrogenation of citrate (decarboxylation) (3)

citrate loses a carboxyl group releasing carbon dioxide as a waste product, a 5-carbon intermediate molecule is formed, 5-carbon intermediate molecule is also decarboxylated forming 4-carbon oxaloacetate again

Outline stage 2 of the Krebs cycle as decarboxylation and dehydrogenation of citrate (dehydrogenation) (4)

at the same time the decarboxylation is occurring, citrate and 5-carbon intermediate are dehydrogenated/oxidised, 3 coenzyme NAD molecules are reduced, 1 coenzyme FAD molecule is reduced

What is stage 3 of the Krebs cycle?

Substrate-level phosphorylation

Outline stage 3 of the Krebs cycle as substrate-level phosphorylation

1 ADP molecule and 1 inorganic phosphate group react to produce 1 molecule of ATP

What are the reactants of the Krebs cycle? (6)

1 x acetyl CoA, 1 x oxaloacetate, 3 x NAD, 1 x FAD, 1 x ADP, 1 x Pi

What are the products of the Krebs cycle? (6)

1 x CoA, 2 x CO2, 3 x NADH, 1 x FADH2, 1 x ATP, 1 x oxaloacetate

How many hydrogen atoms does coenzyme NAD accept?

1

How many hydrogen atoms does coenzyme FAD accept?

2