5.2 Respiration

Question 1

Aerobic vs Anaerobic

Answer 1

Respiration done aerobically (with oxygen) or anaerobically (without oxygen)

Question 2

Mitochondria

Answer 2

Cristae (folds in inner membrane) provide a large surface area to maximise respiration

Question 3

Coenzymes

Answer 3

NAD, coenzyme A and FAD. NAD and FAD transfer hydrogen. Coenzyme A transfers acetate

Question 4

Respiratory substrates

Answer 4

Glucose, fatty acids from lipids, amino acids from proteins

Question 5

Glycolysis (Step 1 Respiration)

Answer 5

1. Glucose phosphorylated by ATP. Creates 1 molecule glucose phosphate and 1 molecule ADP. Phosphorylated again to make hexose bisphosphate. Split into 2 triose phosphates
2. Triose phosphate oxidised, forms 2 pyruvates. NAD reduced and 4 ATP produced

Question 6

Products of glycolysis

Answer 6

2 reduced NAD goes to oxidative phosphorylation, 2 pyruvate actively transported into mitochondrial matrix for link reaction, 2 ATP net gain for energy

Question 7

Glycolysis (Anaerobic)

Answer 7

Pyruvate converted to ethanol in plants and yeast, converted to lactate in animal cells and some bacteria. Regenerates NAD so glycolysis can continue

Question 8

Link reaction (Step 2 Respiration)

Answer 8

Pyruvate decarboxylated and oxidised (NAD reduced) to form acetate. Acetate combined with coenzyme A for form acetyl coenzyme A

Question 9

Products of link reaction

Answer 9

2 acetyl coenzyme A used in Krebs cycle, 2 CO2 released as waste product, 2 reduced NAD goes to oxidative phosphorylation

Question 10

Krebs cycle (Step 3 Respiration)

Answer 10

1. Acetyl CoA forms 6C citrate. Coenzyme reused in link reaction
2. 5C compound decarboxylated and dehydrogenated, produces 1 reduced FAD and 2 reduced NAD. Substrate-level phosphorylation takes place to finish regenerating oxaloacetate

Question 11

Products of Krebs cycle

Answer 11

1 coenzyme A reused in link reaction, oxaloacetate regenerated for use in Krebs cycle, 2 CO2 released as waste, 1 ATP used for energy, 3 reduced NAD goes to oxidative phosphorylation, 1 reduced FAD goes to oxidative phosphorylation

Question 12

Oxidative Phosphorylation (Step 4 respiration)

Answer 12

1. Reduced NAD and reduced FAD oxidised. Hydrogen split into protons and electrons
2. Electrons move down ETC and lose energy
3. Energy used to pump protons from mitochondrial matrix into intermembrane space
4. Electrochemical gradient formed
5. Protons move down electrochemical gradient via ATP synthase
6. Chemiosmosis
7. Oxygen the final electron acceptor

Question 13

Mitochondrial disease

Answer 13

Affects proteins, reducing ATP production. May increase anaerobic respiration to make ATP shortage. Results in lactate, can cause muscle fatigue and weakness. Some may also diffuse into bloodstream