12.3 oxidative phosphorylation

Question 1

where does the electron transport train occur?

Answer 1

cristae of mitrochondria

Question 2

how does the location of the electron transport train help oxidative phosphorylation?

Answer 2

folded inner membrane has high SA + lots of membrane-bound enzymes & proteins

Question 3

describe how ATP is formed by oxidative phosphorylation by electron transport chain. (5)

Answer 3

1) reduced NAD/FAD donates (reduces) 2e- to 1st/2nd electron carrier molecule
2) 2e- passed on by oxidation-reduction reactions
3) energy lost by 2e- is used to pump protons (H+) into intermembrane space, out of matrix
4) H+ diffuses down conc. gradient by facilitated diffusion through ATP synthase & ADP is phosphorylated to ATP by chemiosmosis
5) O2 acts as final e- acceptor & mops up 2e- & 2H+ by forming H2O

Question 4

what happens if there is a lack of O2?

Answer 4

ETC shuts down -> no NAD / FAD produced
-> link reaction & krebs cycle stops

Question 5

how do lipids act as an alternative respiratory substrate?

Answer 5

hydrolysed to 3 fatty acids & 1 glycerol
- fatty acids broken down to 2C -> acetyl coenzyme A -> krebs cycle

• glycerol -> phosphorylated to TP -> glycolysis
• oxidation reaction releases H atoms -> ETC

Question 6

how are proteins used as an alternative respiratory substrate?

Answer 6

hydrolysed to amino acids
- deamination releases amine group -> liver & excreted

• broken down:
  2C - acetyl coenzyme A
  3C - pyruvate
  4-5C - krebs cycle intermediate