Question

"Generally describe the series of events via which pyruvate is further processed after glycolysis (assume that this is in the presence of oxygen, i.e. pathways other than fermentation). Keep track of the net inputs and outputs of these processes and the locations in which they happen.

Answer 1

Answer:

The product of glycolysis is two molecules of pyruvate. It is a three-carbon compound. This pyruvate again undergoes oxidation in the cytoplasm. This process is called pyruvate oxidation which produces Acetyl CoA. The Acetyl CoA is a two-carbon molecule.

Acetyl CoA again used for the citric acid cycle. This is also called as Kreb's cycle / TCA cycle. Because citric acid has 3 carboxylic groups. The acetyl coenzyme produces NADH, FADH2, ATP. The citric acid cycle occurs in the mitochondrial membrane. This is an 8 step process. The first product is citric acid. The other products of each step are isocitrate, alpha-ketoglutarate, succinyl CoA, succinate, Fumarate, L - malate, and Oxaloacetate (OAA).

Another process of aerobic respiration is the electron transport chain ( ETS). Here the energy stored in NADH, FADH2 in the citric acid cycle are utilized. It is a chain of electron carriers. ETS occurs in the inner membrane of mitochondria.  

In short, the glucose splits by glycolysis and produces ATP, NADPH, and final product pyruvate. The pyruvate is oxidized and forms acetyle coenzyme. This is used in the TCA / citric acid cycle. In this process also NADH, FADH2 which forms electrons are produced. Theses electrons are carried by different electron carriers and accepted by oxygen.

In the process of pyruvate oxidation 6 ATP, and in Kreb's cycle 18 ATPs, in ETS, 4 ATPs are produced. In addition to this in glycolysis produces 4 ATPs. The total number of ATP in aerobic respiration is 32 ATP.