Anaerobic

What are the 3 stages in the aerobic energy system?

1. Glycolysis

2. Krebs cycle

3. Electron transport chain

Explain the process of glycolysis

Glycogen in the muscles and liver is broken down by GPP (glycogen phosphorylase) into glucose-6-phosphate, which has 6 carbon molecules. It is then broken down by PFK (phosphofructokinase) into pyruvic acid, which has 2 lots of 3 carbon molecules.

What happens after glycolysis?

The pyruvic acid crosses the mitochondrial membrane and undergoes oxidative decarboxylation in the presence of oxygen which is readily available in the muscle cells, in which the 3rd carbon is removed and joined with O2 to make CO2, which is transported to the lungs and expired. It leaves us with acetyl co-enzyme A which then enters the Krebs cycle.

Where does the Krebs cycle take place?

The matrix of the mitochondria.

Describe the process of the Krebs cycle

It is a cyclical process with lots of chemical reactions. Acetyl Co-enzyme A binds with oxoloacetic acid (a 4 carbon structure) to make citric acid (a 6 carbon structure). Citric acid undergoes oxidative carboxylation which produces 2ATP, CO2 and hydrogen.

Where does the electron transport chain take place?

The cristae of mitochondria

Describe the electron transport chain

Hydrogen ions bind with O2 to create H2O whch is expelled from the body as sweat or in breath. Hydrogen electrons are stripped off to power the resynthesis of ATP by the process of oxidative phosphorylation. This produces 34ATP.

What is the net yield of the aerobic system?

38 ATP

• Glycolysis- 2

• Krebs cycle- 2

• ETC- 34

What happens once we run out of glycogen?

Glycogen stores can power about 60 minutes of exercise. After this, we have burnt through gkycogen so glycolysis can’t occur. We then turn to fat stores, stored as triglycerides. Triglycerides are broken down into glycerol and free fatty acids (which are a 2 carbon chain). This then enters the Krebs cycle.

Give 3 advantages of the aerobic energy system

• Lots of glycogen and triglyceride stores

• High efficiency and yeild of 38ATP

• No fatiguing by-products such as lactic acid

Give 2 disadvantages of the aerobic energy system

• Fatty acid transportation needs 15% more oxygen than glucose

• A long chain of reactions so takes longer to start producing energy