ATP and Carbohydrate Metabolism

Question 1

How does ATP create movement and energy?

Answer 1

myosin converts free energy change of ATP hydrolysis to kinetic energy

Question 2

What is the ATP-ADP cycle?

Answer 2

• ATP is a high energy nucleotide with three phosphate groups attached to a ribose sugar
• the negative charge on the terminal oxygen of the phosphate group acts like a compressed spring as it repels the rest of the molecule
• chemical energy is released from ATP when it is hydrolysed losing a phosphate group
• anabolic reactions are coupled to the hydrolysis of ATP to ADP + Pi + energy to perform cellular work
• catabolic reactions release energy which can be used for ATP synthesis

Question 3

How does the ATP/ADP cycle work during exercise?

Answer 3

• ATP supplies the demand of energy from skeletal muscle and other tissues during exercise
• mechanical energy: muscle contraction
• electrical energy: electrical nerve impulses
• heat: maintenance of body temperature

Question 4

What do square brackets [] mean around ATP?

Answer 4

ATP concentration

Question 5

How long would stored ATP in muscle last during maximal exercise?

Answer 5

~3 seconds

Question 6

How does ATP replenishment / myokinase regulation work?

Answer 6

• myokinase reaction is anaerobic and maintains [ATP] during hard exercise
• the reaction is favoured because:
  
  • reduced [ATP]
  • increased ADP
  • AMP is broken down in the liver and then excreted via the kidneys by adenosine to favour more ATP formation

Question 7

What is the role of phosphocreatine (PCr) system in muscle?

Answer 7

• PCr has the highest phosphoryl transfer potential
• creatine kinase rapidly drives ATP synthesis during hard exercise
• PCr outweighs Cr in muscle to favour the conversion to Cr and ATP
• although PCr stores are 3-4 times larger than ATP, the resynthesis of PCr stores is slower than ATP
• PCr stores last ~7 seconds during maximal exercise