Describe : Tricarboxylic acid cycle OR describe Kreb's cycle

Explanation

The TCA cycle start with the condensation of acetyl group with oxaloacetic acid (OAA) and water to yield citric acid. The reaction is catalysed by the enzyme citrate synthase and a molecule of CoA is released.
`OA A (4C) + "Acetyl "CoA + H_(2) O (2C) underset("Citrate synthatase")to` Citric acid 6C + CoA
Citrate is then isomerised to isocitrate.
It is following by two successive steps ofdecarboxylation, leading to the formation of `alpha`- ketoglutaric acid and then succinyl-CoA
Citric acid `to` Iso Citrate `to alpha` - ketoglutaric acid
Remaining steps of citric acid cycle :
Succinyl-Coa is oxidised to OAA allowing the cycle to continue.
During the conversion of succinyl-CoA to succinic acid a molecule of GTP is synthesized .
This is a substrate level phosphorylation.
In a coupled reaction GTP is converted to GDP with the simultaneous synthesis of ATP form ADP.
`GTP to GDP + Pi to ADP + Pi to ATP`
Also there are three points in the cycle where `NAD^(+)` is reduced to NADH + `H^(+)` and one point where `FAD^(+)` is reduced to `FADH_(2)` .The continued oxidation of acetyl CoA Via the TCA cycle requires the continued replenishment of oxaloacetic acid
It is the first member of the cycle . In addition it also requires regeneration of `NAD^(+) and FAD^(+)` from NADH and `FADH_(2)` respectively
The summary equation for this phase of respiration may be written as follow :
Pyruvic acid `+ 4NAD^(+) + FAD^(+) + 2H_(2) O + ADP + Pi underset("Matrix")overset("Mitochondrial")to `
`3CO_(2) + 4NADH + 4H^(+) + FADH_(2) + ATP`
Glucose has been broken down to release `CO_(2)` and eight molecules of `NADH + H^(+)` , two of `FADH_(2)` have been synthesised besides just two molecules of ATP in TCA cycle .