Pyruvate Oxidation + Krebs Cycle

SBI4U - Birrell

Pyruvate Oxidation and the Krebs Cycle both take place in the _________ ______

mitochondrial matrix

what does pyruvate oxidation do? (generally/in terms of the carbon)

transforms each pyruvate into an acetyl-CoA

what happens to pyruvate during pyruvate oxidation? (3)

• pyruvate is decarboxylated — removed as CO₂

• remaining 2-C sugar is oxidized — NAD+ is reduced (forms NADH)

• CoA attaches, forming Acetyl-CoA

CoA is short for

Coenzyme A

Pyruvate Oxidation yields:

• 2 CO₂

• 2 NADH

• 2 Acetyl-CoA

to enter the mitrochondrial matrix, pyruvate uses a __________ _________

transport protein

what does the krebs cycle do?

generates energy carriers (NADH, FADH2) and also ATP

the krebs cycle is also called the _________ ______ cycle because the ______ molecule that it forms is citrate

citric acid, first

why is the krebs cycle considered a “cycle”?

because the product becomes the initial reactant of the next set of reactions

In the first step of the krebs cycle, the _______ portion combines with a __-Carbon molecule called ____________.

acetyl, 4, oxaloacetate

the final product and intial reactant of the krebs cycle is called:

oxaloacetate (4 Carbons)

what happens to the CoA during formation of citrate?

it comes off/is released

What happens after the formation of citrate? (8)

• citrate undergoes isomerization

• the product is oxidized and decarboxylated x2 times — 2 NAD+ reduces to a NADH and a CO₂ is released

• CoA attaches to the 4-C molecule — becomes succinyl-CoA

• succinyl-CoA loses CoA, and either ADP is phosphorylated (form ATP) or GDP is (form GTP)

• the molecule is oxidized — FAD is reduced to FADH₂

• water is added (fumarate → maleate)

• the molecule is again oxidized — NAD+ is reduced to NADH

• oxaloacetate is formed and the cycle repeats

the Krebs Cycle yields:

• 4 CO₂

• 6 NADH

• 2 ATP

• 2 FADH₂

• 2 oxaloacetate