Question

How are glycolysis, Krebs TCA cycle and the electron transport chain linked?

Answer 1

Aerobic respiration occurs in main four steps, namely glycolysis, link reaction, Krebs (TCA) cycle and electron transport chain (ETC).

Glycolosis: It is partial oxidation of glucose to form two molecules of pyruvate, two NADH, and two ATP. Glycolysis occurs in the cytoplasm.

Link Reaction: After entering mitochondria, pyruvate undergoes oxidative decarboxylation to form acetyl Co-A and NADH. CO${}_2$ is released.2 is released.

Krebs Cycle: Acetyl Co-A reacts with oxaloacetate. The product, citrate, undergoes two oxidative decarboxylations and two dehydrogenations. Oxaloacetate is regenerated. The byproducts are 3 NADH, 1 FADH22, 1 ATP or GTP and 2CO${}_2$2. Krebs Cycle occurs inside mitochondria.

Terminal Oxidation: NADH and FADH are oxidized. The energy liberated during oxidation is used in the synthesis of ATP and ADP and inorganic phosphate. Hydrogen is ultimately oxidized by oxygen to form water. Terminal oxidation takes place over the inner membrane of mitochondria.