Energy I

Question 1

What is catabolism? [1 mark]

Answer 1

The breakdown of complex molecules to release energy or carry out mechanical work.

Question 2

What is anabolism? [1 mark]

Answer 2

Synthesis of new molecules from less complex components.

Question 3

What is the total energy available from ATP? [1 mark]

Answer 3

65kJ/mol

Question 4

How much ATP does the body need? [1 mark]

Answer 4

100g

Question 5

What factors regulates enzymes for glycolysis? (NOT ENZYMES) [3 marks]

Answer 5

• Reverse binding of allosteric effectors
• Covalent modification
• Transcription

Question 6

What inhibits hexokinase? [1 mark]

Answer 6

Glucose-6-phosphate

Question 7

What inhibits phosphofructokinase (PFK)? [3 marks]

Answer 7

• ATP: lowers affinity for fructose-6-phosphate (F6P)
• Citrate: if there’s enough citrate, glycolysis can be slowed down
• H+ (low pH)

Question 8

What happens if PFK is inhibited? [1 mark]

Answer 8

Hexokinase is also inhibited

Question 9

How does AMP activate PFK? [3 marks]

Answer 9

• When a cell is very low on ATP, it will start squeezing more ATP out of ADP molecules
• ADP + ADP → ATP + AMP
• High levels of AMP mean that the cell is starved for energy

Question 10

What indirectly stimulates PFK? [1 mark]

Answer 10

Build up of F6P

Question 11

What inhibits glycolysis in anaerobic conditions? [1 mark]

Answer 11

H+ from lactate

Question 12

Why do tumours use anaerobic respiration? [2 marks]

Answer 12

• Tumours outgrow their blood supply

- Oxygen delivery is reduced

Question 13

When is Hypoxia Inducible Factor (HIF-1-alpha) activated? [1 mark]

Answer 13

When there’s low O2 levels in tumours

Question 14

What does HIF-1-alpha do? [3 marks]

Answer 14

• Regulates expression of proteins in glycolytic pathway
• Including GLUT1, GLUT2 and hexokinase
• Stimulates blood vessel growth (angiogenesis)

Question 15

Stability of HIF-1-alpha [2 marks]

Answer 15

• Unstable

- Stabilised in low concentrations of O2