Lesson 2.

Aerobic energy system.

Aims:To revise the phosphocreatine system and lactic acid energy system.

To know the key functional characteristic of the aerobic energy system.

To understand the positive and negative aspects of this system.

PC + Lactic acid energy system questions.

1. Why is the phosphocreatine energy system a coupled reaction [1]?

Answer: because the energy produced in one reaction is used by another reaction.

2.Write an equation showing the resynthesis of ATP using the phosphocreatine system [2].

Answer: PC=P+C+ENERGY (exothermic)

ENERGY+ADP+P=ATP (endo)

3. Describe 2 advantages and 2 disadvantages of the phosphocreatine

energy system [4].

Provides energy for 10secs.No harmful by-products

One mole of ATP is re-synthesised form one mole of PC.

O2 is not required.

Small amount stored in muscle cells.Provides ATP re-synthesis quickly.

Disadvantage.Advantage.

4. Name the enzyme that initiates anaerobic glycolysis [1].

Answer: Phosphofructokinase (PFK).5. During anaerobic glycolysis how many ATP moles are re-synthesised? [1].Answer: 2.6. What is the name of the acid which is eventually converted into lactic acid? [1].Answer: Pyruvic acid.7. Pyruvic acid is converted into lactic acid by which enzyme? [1].Answer: lactate dehydrogenase (LDH).

8. Name 2 advantages and 1disadvantage of the lactic acid energy system [3].

No delay due to the lack of O2 required.

Lasts from 15-180 seconds.e.g. 400m

ATP provided quickly.

Lactic acid produced reduced blood pH making it more acidic preventing enzymes from functioning properly.

Provides more ATP than PC system.

Disadvantage.Advantage.

The Aerobic energy system

This system requires O2 and Glycogen or fat to resynthesis ATP.When would fat be used?When O2 is readily available and the intensity of exercise is moderate, the pyruvic acid is moved to another set of chemical reactions instead of being converted into lactic acid.This is the junction from using the lactic acid system and the aerobic system!!!!!!!!What type of sporting activities use the aerobic energy system?

The Kreb’s Cycle.The pyruvic acid is taken by the enzyme acetyl CoA into the Kreb’s cycle in the mitochondria (matrix).

Glycogen

Pyruvic acid

2 ATP

Lactic acid

Kreb’s cycle

sarcoplasm

Mitochondria matrix

2 ATP2CO2 Removed via lungs

Acetyl CoA

Electron transfer chainN.B if fat is being used as an energy source it enters the Kreb’s cycle as fatty acids and beta oxidation occurs.

The hydrogen from the Kreb’s cycle enters the next series of reactions known as ETC.

This occurs in the mitochondria cristae.

Electrons are removed from hydrogen and passed down the electron chain providing 34moles of ATP.

Hydrogen combines with O2 to produce water which is expelled out of the body.

The ETC.

Krebs cycle

Hydrogen

ETC

O2

H2O 34ATP

Mitochondria matrix.

Mitochondria cristae

The advantages and disadvantages of the aerobic

energy system.

No harmful by-products.

Cannot provide ATP at high intensity work levels.

Activity can last hours.

The system cannot re-synthesis ATP instantly because of the delay in O2 transportation.

Large amount of ATP is re-synthesised 36-38 moles of ATP from one mole of glycogen.

Disadvantages Advantages