respiration

Question 1

4 steps for aerobic respiration

Answer 1

1. Glycolysis - cytoplasm (anaerobic)
2. Link reaction - mitochondrial matrix
3. Krebs cycle - mitochondrial matrix
4. Oxidative phosphorylation - inner
   mitochondrial membrane

Question 2

glycolysis

Answer 2

1. Glucose phosphorylated to glucose phosphate
   Using inorganic phosphates from 2 ATP
   Hydrolysed to 2 x triose phosphate
   Oxidised to 2 pyruvate
   ○ 2 NAD reduced
   ○ 4 ATP regenerated (net gain of 2)

Question 3

what happens after glycolysis if anaerobic respiration

Answer 3

1. Pyruvate converted to lactate or ethanol
2. Oxidising reduced NAD → NAD regenerated
3. So glycolysis can continue
   allowing continued production of ATP

Question 4

links

Answer 4

1. Pyruvate oxidised (and decarboxylated) to acetate
   ○ CO2 produced
   ○ Reduced NAD produced (picks up H)
2. Acetate combines with coenzyme A, forming Acetyl
   Coenzyme A
   products per glucose
   2 AC 2 co2 2 reduced nad

Question 5

krebs

Answer 5

1. Acetyl coenzyme A (2C) reacts with a 4C molecule
   ○ Releasing coenzyme A
   ○ Producing a 6C molecule that
   enters the Krebs cycle
2. In a series of oxidation-reduction
   reactions, the 4C molecule is
   regenerated and:
   ○ 2 x CO2
   lost
   ○ Coenzymes NAD & FAD reduced
   ○ Substrate level phosphorylation
   (direct transfer of Pi from
   intermediate compound to ADP)
   → ATP produced

Question 6

krebs products per glucose

Answer 6

6 x reduced NAD,
2 x reduced FAD, 2 x ATP and 4 x CO2

Question 7

Oxidative phosphorylation

Answer 7

1. Reduced NAD/FAD oxidised to release H atoms → split into protons (H
   +
   ) and electrons (e
   -
   )
2. Electrons transferred down electron transfer chain (chain of carriers at decreasing energy levels)
   ○ By redox reactions
3. Energy released by electrons used in the production of ATP from ADP + Pi (chemiosmotic theory):
   ○ Energy used by electron carriers to actively pump protons from matrix → intermembrane space
   ○ Protons diffuse into matrix down an electrochemical gradient, via ATP synthase (embedded)
   ○ Releasing energy to synthesise ATP from ADP + Pi
4. In matrix at end of ETC, oxygen is final electron acceptor (electrons can’t pass along otherwise)
   ○ So protons, electrons and oxygen combine to form water