Metabolism 1 & 2

Question 1

What are the underlying principles of metabolism (2)

Answer 1

1. catabolism = breaking down larger molecules into smaller units - △G = -ve (exergonic)
2. anabolism = building larger molecules from smaller units - △G = +ve (endergonic)

Question 2

What are the stages of carbohydrate digestion (4)

Answer 2

1. carbohydrates → glucose and other monosaccharides
2. glycose → x2 pyruvate (via glycolysis) → acetyl-CoA
3. acetyl-CoA → krebs cycle
4. electron transport chain → ATP synthesis

Question 3

What are the stages of lipid digestion (4)

Answer 3

1. lipids → fatty acids and glycerol
2. fatty acids → acetyl-CoA (via the fatty acid cycle)
3. acetyl-CoA → krebs cycle
4. electron transport chain → ATP synthesis

Question 4

What are the stages of protein digestion (4)

Answer 4

1. Proteins → amino acids
2. amino acids → acetyl-CoA (via the amino acid cycle) → Krebs cycle intermediate
3. Krebs cycle → electron transport chain
4. electron transport chain → ATP synthesis

Question 5

How are phosphates used as energy transfer systems (2)

Answer 5

1. Glucose-6-phosphate + H2O → Glucose + phosphoric acid (low energy phosphate)
2. Phosphoenolpyruvate + H2O → Pyruvate + Phosphoric acid (high energy phosphate)

Question 6

What happens during ATP, ADP and AMP hydrolysis (3)

Answer 6

1. ATP + H2O → ADP + Phosphoric acid
2. ADP + H2O → AMP + Phosphoric acid
3. AMP + H2O → Adenosine + Phosphoric acid

Question 7

What is oxidation (3)

Answer 7

1. Loss of electron(s)
2. Gain of oxygen
3. Loss of hydrogen

Question 8

What is reduction (3)

Answer 8

1. Gain of electron(s)
2. Loss of oxygen
3. Gain of hydrogen

Question 9

What is the concept of reduced co-enzymes (4)

Answer 9

1. The important aerobic oxidation of NADH and FADH2
2. Oxidation of NADH and FADH2 forces the electron transport chain to synthesise ATP.
3. 3 molecules of ATP formed from the oxidation of NADH
4. 2 molecules of ATP formed from the oxidation of FADH2

Question 10

What are the stages of catabolism (4)

Answer 10

1. oxidise NADH and FADH2
2. Glycolysis, Aerobic or anaerobic conditions: fatty acid cycle (beta-oxidation) or amino acid cycle
3. Tricarboxylic Acid (TCA) Cycle, Krebs Cycle or Citric Acid Cycle (aerobic conditions only)
4. Electron Transport Chain (ETC) and Oxidative Phosphorylation

Question 11

How is metabolism controlled (6)

Answer 11

1. feedback control or inhibition of enzymes
2. Kinases
3. Phosphatases
4. Mutases
5. Isomerases
6. Dehydrogenases