Question

Diagram and describe the oxidative energy system. Be detailed in where the various steps in the aerobic process occur and give an ATP accounting for all major steps.

Answer 1

OXIDATIVE energy system in aerobic process is also known as Krebs cycle/TCA cycle/citric acid cycle.As we know the main energy source in our body is glucose,which comes from carbohydrates.In oxidative system oxygen is used from carbohydrates and fats.The energy currency we get in the form of ATP.

The process of TCA cycle occur in the mitochondria of cells.After glycolysis (which occur in cytosol ),we get pyruvic acid.The Pyruvic acid not directly enter into TCA cycle it first converted into acetyl coA by redox reaction ,means 3carbon containing Pyruvic acid changes into 2carbon containing Acetyl coA after releasing 1molecule of CO2.

There are several steps occur in TCA cycle and finally one molecule of acetyl coA gives 1ATP . As we know1molecule of glucose gives 2 pyruvic acid means 2acetyl coA..so 2ATP will produce.And indirectly NADH and FADH2 is also gives ATP in last step of shuttle system.Normally 1NADH convert into 2.5 ATP and 1FADH2 gives 1.5 ATP.

Steps:

1 .Acetyl coA is accepted 4 carbon containing compound oxaloacetic acid and we get citric acid which is 6 carbon compound. Enzymes helping in this step is citrate synthase.

2. Citric acid changes into its isomer called isocitrate.Also 6 carbon compound.

3.Isocitrate is converted into 5 carbon compound Alpha ketoglutarate after release one carbon dioxide.It is also a redox reaction where NAD gets converted into NADH2.

4.Alpha ketoglutarate converted into four carbon containing compound into succinyl coenzyme after release of one carbon dioxide and addition of one coenzyme. In this step NAD also converted into NADH2.

5.Succinyl coenzyme a simply converted into succinic acid ,so in this reaction coA is released and energy is also released GDP to GTP or we can say GTP also converted into ATP.(means GTP indirectly gives ATP.)

6.Succinic acid changes into fumarate this is also a redox reaction, this time in redox reaction FAD reduce to FADH2.

7.In this step fumarate changes in malate.

8 .Malate changes into Oxaloacetic acid which is also a redox reaction where NAD gets converted into NADH2.

Diagram:: Detailed explanation with enzymes and steps.....