Name: Amphibolic Pathway
Uploaded: 2019-07-19
Duration: 6 min 24 s
Description: The amphibolic pathway is the biochemical pathway that comprises both catabolic and anabolic processes. The respiratory pathway serves as a great model to st...

Question

Describe the reaction steps of Kreb's cycle.

Accepted Answer

Kreb's cycle is also known as the citric acid cycle or tricarboxylic acid cycle (TCA), as described by Hans Kreb. It occurs in the mitochondrial matrix when pyruvate converts into a 2-carbon-containing acetyl CoA molecule.

Acetyl CoA combines with a 4-C containing OAA and forms a 6-C molecule, citrate. It undergoes a rearrangement reaction involving removal and then the addition of a water molecule producing an isocitrate isomer.

Isocitrate oxidizes to produce one CO₂ molecule and alpha-ketoglutarate in the presence of the enzyme isocitrate dehydrogenase.

The alpha-ketoglutarate oxidizes, and NAD⁺ is reduced to NADH with the release of one CO₂ molecule, forming succinyl CoA.

Succinyl CoA releases CoA, and phosphate is added, which will be later transferred to ADP for ATP and succinate formation.

Succinate oxidizes to fumarate, with the formation of FADH₂.

Fumarate converts into malate, oxidation of which produces OAA with one NADH formation from NAD⁺.

There is a net gain of 3 NADH₂, 1 FADH₂, and 1 ATP or GTP after the completion of one Kreb's cycle.

Describe the reaction steps of Kreb's cycle.

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