W1 - Anaerobic Energy Provision

Question 1

How much energy is released from the hydrolysis of one ATP molecule?

Answer 1

ATP + H2O = ADP + Pi
= 30.5 kJ/mmol

Question 2

In the muscle what type of ATPase hydrolyses ATP for a muscle contraction?

Answer 2

Myofibrillar ATPase (activity of myosin head ATPase)

Question 3

What is the time duration of muscle contractions that can be undergone from the cells stored ATP ?

Answer 3

2 seconds worth of maximum contractions

Question 4

What is the ATP yield from 1 mol of PCr?

Answer 4

1 mol ATP

Question 5

What is the exercise duration where the ATP-PCr system can be used?

Answer 5

3-15 seconds of maximal exercise e.g.: weightlifter/sprinter

Question 6

How does creatine kinase control the rate of ATP production in the ATP-PCr system

Answer 6

Negative feedback system:
* When ATP levels decrease (ADP increase), CK activity increase
* When ATP levels increase, CK activity decrease

Question 7

Describe how the ATP-PCr system works and what substrates are formed

Answer 7

PCr broken down to Cr + Pi + free energy
then free energy + Pi added to ADP creates ATP

Question 8

Provide a reason why creatine may not be optimal for sprinters performance

Answer 8

The osmotic activity of Creatine, the high cell water content can cause weight gain. This is why it is not excessively high in sprinters

Question 9

What is Myokinase?

What are some drawbacks of the Myokinase reaction?

Answer 9

An enzyme that uses 2x ADP from muscle contraction(myosin and actin detaching)
- forms ATP and AMP

• Limited capacity to produce ATP(more ADP available the faster the myokinase reactions
• Only important during high intensity exercise (activated when pH falls)
• AMP is activator of enzymes involved in glycogen breakdown

Question 10

What role does PFK play in glycolysis?

Answer 10

Rate-limiting enzyme
* decrease ATP (increase ADP) → PFK activity increase
* increase ATP → PFK activity decrease

Question 11

What is the rate limiting enzyme of Glycolysis?
what are the other 2 important enzymes in glycolysis?

Answer 11

• phosphofructokinase (PFK)
• phosphorylase and lactate dehydrogenase (LDH)

Question 12

What is the ATP yield per mol of substrate from aerobic glycolysis from
1. Glucose
2. Glycogen
3. Lactate

Answer 12

1. 2 mol ATP per mol of substrate glucose
2. 3 mol ATP per mol of substrate glucose
3. 1-1.5 mol ATP per lactate if all pyruvate is converted to lactate

Question 13

At what exercise duration is glycolysis used?

Answer 13

Duration: 15 s to 2 min

Question 14

Name the two main enzymes in the Krebs cycle in Glycolysis

Answer 14

Citrate synthesis and Succinate dehydrogenase

Question 15

How does training impact the concentration of aerobic and anaerobic enzymes?

Answer 15

• Aerobically trained individuals have higher concentration of aerobic enzymes (oxidative system)
• Anaerobically trained individuals have higher concentration of anaerobic enzymes (ATP-PCr & Glycolytic system)

Question 16

What does the Wingate test test for?

Answer 16

anaerobic variables
* Wingate test (30-s all-out sprint) on cycle ergometer
* Applying the correct load (traditionally: ~7.5% of body mass)
* Determination of peak power, fatigue index

Question 17

What is the equation for fatigue index(%)

Answer 17

fatigue index(%) = (Peak power - lowest power)/Peak power * 100