the biochemGazettE: TCA Vid Review….


Well back again, this time am gonna review the TCA/ Krebs/ Citric Acid Cycle it gonna be a vid review  part reflection

Reflection: TCA that’s another old foe. He was scary but he ain’t, so this cycle unlike glycolysis needs oxygen and it occurs in two cycles for every 1 glucose molecule and where it actually occurs is in the matrix of the mitochondria. Also something new i learn’t maybe due to my ignorance is that one of the enzyme Succinate Dehydrogenase is found in the inner membrane of the mitchondria unlike the rest of the enzymes which are in the matrix.

This vid came from the same ppl who I reviewed on the Glycolysis, can’t help it love the voice and the clear drawings. So, Krebs cycle is the 3 step in glycolysis if we’re gonna count the preparatory step as one in this cycle we’re oxidizing 2 Acetyl-CoA to form:

4 oxygen+ 2ATP + 6 NADH+ 2FADH2

So , he started of with identifying that pyruvate is the krebs cycle primary substrate although their are other substrate than can be used eg. fatty acids. He also looked at the preparatory stage where the pyruvate from glycolysis is converted to Acetyl-CoA by pyruvate dehydrogenase complex and that it had other substance assisting it in the conversion ie. cofactors.  He cleary went through all the steps, but also he identified the enzymes involved in each intermediate conversion which was a bonus


1. Citrate Synthase- forms citrate from acetyl-CoA and oxaloacetate

2. Aconitase- converts citrate to cis-aconitate

3. Aconitase again converts cis-aconitate back to isocitrate (a isomer of citrate)

4. Isocitrate Dehydrogenas- converts isocitrate to alpha-ketogluterate and gives off the first NADH and first CO2

5. Alpha-Ketogluterate Dehydrogenase Complex- converts alpha-ketogluterate to succinyl-CoA and gives off the second CO2 and NADH.

6. Succinyl-CoA Synthetase- converts succinyl-CoA to Succinate and gives off GTP which is a form of ATP.

7. Succinate Dehydrogenase- converts Succinate to Fumarate and givess of the ony FADH2.

8. Fumarase- converts fumarate to Malate.

9. Malate Dehydrogenase- converts malate back to oxaloacetate and the final NADH of this cycle.

So all in all a good and concise overview of the Krebs Cycle.