Question

LONUdly acuve transport. Chapter 13 What are the major events of cellular respiration (glycolysis, pyruvate processing etc)? Where does each occur? What are the products? Where is the energy in each step? Where is the carbon in each step? LLLL D Focus

Answer 1

The main events of aerobic respiration are as follows:

a. Glycolysis

b. Oxidative decarboxylation of pyruvate

c. Krebs cycle or citric acid cycle

d. Electron transport chain

Glycolysis

1. It is a multistep metabolic pathway and takes place in the cytosol of a cell.

2. In glycolysis 6 carbon glucose molecule is broken down into two molecules of 3 carbon pyruvate.

3. 2 ATP molecules and 2 NADH molecules are the products of glycolysis.

Oxidative decarboxylation

1. Pyruvate after entering into the mitochondria is processed by a multienzyme complex known as pyruvate dehydrogenase.
2. In this process pyruvate is converted into acetyl co-A and there is loss of one carbon dioxide molecule from the each molecule of pyruvate.

3. Two molecules of NADH are also generated.

4. This reaction takes place in the mitochondrial matrix.

Krebs cycle

1. Krebs cycle is a series of cyclic reactions that begins with the transfer of acetyl group from coenzyme A to the oxaloacetate to form the citric acid.

2. Krebs cycle oxidise the acetyl group completely into water and carbon dioxide producing 3 NADH, 1 FADH2 and 1 ATP per molecule of pyruvate.
3. Krebs cycle takes place in the mitochondrial matrix.

Electron transport chain

1. It is composed of series of electrons carriers located in the inner mitochondrial membrane.

2. These electrons carriers shuttles electrons from NADH and FADH2 to the molecular oxygen.

3. In this process protons are pumped from the matrix into the inter membrane space generating the proton gradient.

4. Proton gradient generates ATP with the help of ATP synthase.