Good morning everybody, (yes once again I am here) but its all in the name of science.
So a lot of people have this idea that once pyruvate is produced thats it! IT IS FINISHED. Well I would know this as I was one of the person who thought that it just went onto the electron transport cycle.But I learned something completely different in class today and it is called THE FATES OF PYRUVATE-THE EVOLUTION!
So here comes along a glucose molecule and it produces two pyruvate molecules. What happens after this?
Well as in the famous words of JM himself ” First you have to ask yourself the question, is oxygen present or is it missing in action”
If oxygen is present then the linkage reaction takes place. Basically this is where pyruvate is converted to Acetyl-CoA by the enzyme pyruvate dehydrogenase. The cofactors are CoA-SH,NAD+,TPP,Lipotate and FAD.
If oxygen is missing in action (anaerobic conditions) pyruvate can go through two processes. These are know as fermentation. Pyruvate can be fermented to ethanol and two carbon dioxide and this is normally done by yeast. Pyruvate is first converted to acetaldehyde ( by the enzyme pyruvate decarboxylase) and then to ethanol ( by alcohol dehydrogenase). NADH goes to NAD+ during this conversion. The co factors for this reaction is TPP and Mg2+.
On the other hand the pyruvate can be fermented to lactate. This occurs in muscle cells. Pyruvate is converted to lactate by the enzyme lactate dehydrogenase. This occurs in mature red blood cells. An interesting fact to note about red blood cells is that they have no mitochondria, so the can not perform the linkage reaction and the RBC depends solely on glycolysis in order to obtain energy.
The big picture for fermentation is that it replenishes NAD+ in a cell. A cell has limited amounts of NAD+ and this is needed to glycolysis. Without NAD+ glycolysis will not countinue and the cells will not be able to produce ATP! And we all know what that means! NO ENERGY!
So I hope I have made it a little clearer for you and summed up the fates of pyruvate in a nice revision blog.Study hard and eat a food people. I out!