Sports science - energy metabolism

Question 1

How is energy released from food?

Answer 1

• food sources are broken down to be used by our cells
• energy is transferred from food sources to ATP via phosphorylation
• ATP is a high-energy compound for storing and conserving energy
• ATP stores in the muscle are limited and therefore must be continuously re-synthesised to maintain PA

Question 2

What are the 3 bioenergetics?

Answer 2

• formation of ATP
• anaerobic pathways
• aerobic pathways

Question 3

Simple glycolysis process

Answer 3

1. glucose -> 2 pyruvic acid
2. energy investment phase - requires 2 ATP
3. energy generation phase - produces 4 ATP, 2 NADH, 2 pyruvate

Question 4

What is the efficiency of glycolysis?

Answer 4

30%

Question 5

What is the net gain in glycolysis?

Answer 5

2 ATP molecules

Question 6

Why do we transport hydrogen and associated electrons?

Answer 6

• to mitochondria for ATP generation (aerobic)
• to convert pyruvic acid to lactic acid (anaerobic)

Question 7

How is NADH converted back into NAD

Answer 7

• by converting pyruvic acid to lactic acid
• by “shuttling” H+ into the mitochondria
• a specific transport system shuttles H+ across the mitochondrial membrane

Question 8

Krebs cycle process

Question 9

What is the electron transport chain process to produce aerobic ATP?

Answer 9

• oxidative phosphorylation occurs in the mitochondria
• electrons removed from NADH and FADH are passed along a series of carries to produce ATP
  . each NADH produces 2.5ATP
  . each FADH produces 1.5ATP
• H+ from NADH and FADH are accepted by oxygen to form water

Question 10

Where does the krebs cycle occur?

Answer 10

mitochondrion matrix

Question 11

What is the krebs cycle also known as?

Answer 11

tricarboxylic acid cycle (TCA)

Question 12

What is pyruvate irreversibly converted to?

Answer 12

acetyl-CoA

Question 13

What is the most important function of the krebs cycle?

Answer 13

the generation of electrons (hydrogen) for transfer to the electron transport chain by means of NAD+ and in one instance FAD

Question 14

What is the control of bioenergetics?

Answer 14

• rate limiting enzymes
  . an enzyme that regulates the rate of a metabolic pathway
• modulators of rate-limiting enzymes
  . levels of ATP and ADP+Pi
  . high levels of ATP inhibit ATP production
  . low levels of ATP and high levels of ADP+Pi stimulates ATP production
  . calcium may stimulate aerobic ATP production

Question 15

What is the interaction between aerobic and anaerobic ATP production

Answer 15

• energy to perform exercise comes from an interaction between aerobic and anaerobic pathways
• effect of duration and intensity
  . short term, high intensity activities = greater contribution of anaerobic energy systems
  . long term, low to moderate intensity exercise = majority of ATP produced by aerobic sources