Question

1. Where are different Krebs cycle enzyme localized in mitochondria? Who is the odd one out in terms of its location? Explain why Acetyl CoA is a hub in the catabolic network of metabolism? Most enzymes in the citric acid cycle belong to the class known as ______________. What kind of reactions do they catalyze and what common kinds of byproducts do they produce?
2. What is the structure of the mitochondria and what are the various membranes and compartments of the mitochondria in order from outside to inside?
3. What are activated electron carriers in glycolysis, in TCA cycle?

Answer 1

The Krebs cycle enzymes are membrane proteins found within the matrix of the mitochondria except for succinate dehydrogenase which is an integral membrane protein present in the inner mitochondrial membrane.

Acetyl Co-A is the hub in the catabolism as it is in this form only it enters into Citric acid cycle a major degradative aerobic pathway i.e. Its main function is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production. It participates in both the citric acid cycle and the electron transport chain.

Most enzymes in the citric acid cycle belong to the class known as dehydrogenases. A dehydrogenase is an enzyme belonging to the group of oxidoreductases that oxidizes a substrate by reducing an electron acceptor, usually NADH /NAD OR FADH2/ FAD.

Mitochondria is made of two membranes. The outer membrane is continuous and the inner one is folded around itself. The minute folds are called cristae. The area inside the membrane is called the matrix. The order of the compartments from outside to inside is-  outer membrane, the intermembrane space, the inner membrane, and the cristae and matrix.

The NADH and FADH2 are activated electron carriers that are formed in glycolysis and Kreb`s cycle which can be used by the electron transport chain (ETC).