Bioenergetics and exercise metabolism

Question 1

What is bioenergetics?

Answer 1

 Flow and exchange of energy within a living system
 Conversion of foodstuffs (fats, proteins, carbohydrates) into
usable energy for cell work.
‘Chemical → mechanical’

Question 2

What does endergonic mean?

Answer 2

Endergonic: Requires energy to
be added to the reactants

E.g., glycogen formation

Question 3

What does exergonic mean?

Answer 3

Exergonic: Releases energy

E.g., ATP hydrolysis

Question 4

What is a coupled reaction?

Answer 4

Coupled reactions: Liberation of energy in an exergonic reaction drives an endergonic reaction.

Question 5

What does a kinase do?

Answer 5

Add a phosphate group

Question 6

What does a dehydrogenase do?

Answer 6

Remove hydrogen atoms

Question 7

What is the rate-limiting enzyme of the ATP-PC system, and what stimulates and inhibits it?

Answer 7

Creatine kinase
stim - ADP
inhib - ATP

Question 8

What is the rate-limiting enzyme of glycolysis, and what stimulates and inhibits it?

Answer 8

Phosphofructokinase
stim - ADP, AMP, Pi, increase pH
inhib - ATP, CP, citrate, decrease pH

Question 9

What is the rate-limiting enzyme of the citric acid cycle, and what stimulates and inhibits it?

Answer 9

Isocitrate dehydrogenase
stim - ADP, Ca2+, NAD+
inhib - ATP, NADH

Question 10

What is the net ATP gain with glycolysis if glucose is the substrate?

Answer 10

2 ATP

Question 11

What is the net ATP gain with glycolysis if glycogen is the substrate?

Answer 11

3 ATP

Question 12

How many pyruvate molecules does glycolysis generate?

Answer 12

2

Question 13

How is citrate formed in TCA cycle?

Answer 13

Acetyl-CoA + oxaloacetate

Question 14

How many ATP molecules per NADH and FADH molecules?

Answer 14

2.5 per NADH
1.5 per FADH

Question 15

What is the aerobic ATP tally per glucose molecule?

Answer 15

32 (textbook definition)

Question 16

What is an oxygen deficit?

Answer 16

Discrepancy between initial demand/ATP production and oxygen consumption

Question 17

What is oxygen debt (EPOC = better term)?

Answer 17

Oxygen uptake remains elevated above rest during recovery from exercise - repayment for O2 deficit at onset of exercise

Question 18

What is magnitude and duration of EPOC influenced by?

Answer 18

Exercise intensity

Question 19

What are the underpinning components of the rapid portion of EPOC?

Answer 19

• PCr resynthesis of stored PCr in muscle (complete recovery 60-120s)
• Repleneshing muscle (myoglobin) and blood (haemoglobin) O2 stores.

Question 20

What are the underpinning components of the slow portion of EPOC?

Answer 20

• Elevated heart rate and breathing increase O2demand
  *Elevated body temperature = increased metabolic rate
  *Elevated blood levels of epinephrine and norepinephrine = increase metabolic rate
  *Conversion of lactic acid to glucose (gluconeogenesis)