Oxidative Phosphorylation

Question 1

Where does Oxidative Phosphorylation take place?

Answer 1

Inner-Mitochondrial membrane

Question 2

2 Parts to Oxidative Phosphorylation:

Answer 2

Electron Transport
ATP Synthesis

Question 3

Electron Transport involves how many protein complexes?

Answer 3

4

Question 4

Which of the 4 protein complexes in Electron Transport are Proton Translocating Complexes?

Answer 4

Protein complex I
Protein complex III
Protein complex IV

Question 5

What is proton motive force (p.m.f)

Answer 5

The proton gradient created by the inner mitochondrial membrane being impermeable to H+ and the 3 Proton Translocating Complexes pumping H+ into the inner mitochondrial membrane space using the energy Fromm the electrons

Question 6

Proton Translocating Complex role

Answer 6

Convert the chemical bond energy of the electrons into an electro-chemical potential difference of protons (p.m.f)

Question 7

NADH electrons have more energy than FADH2 electrons

Answer 7

NADH uses all 3 PTCs (Oxidised at Protein Complex 1)
FADH2 uses only 2 PTCs (contributes less to p.m.f) (Oxised at protein complex 2)

Question 8

Oxygens importance in OXidative Phosphorylation

Answer 8

Terminal/final electron acceptor
Process Ceases if electrons not removed since electrons wont flow so ATP made very slowly

Question 9

How does ATP Synthesis happen through ATP Synthase?

Answer 9

Only permeable part of the membrane to H+ is ATP Sythase
H+ move down proton gradient from inner membrane space back into matrix and ATP Synthase uses this energy from the p.m.f to synthesis ATP

Question 10

Oxidative phosphorylation VS Substrate Level Phospphorylation

Answer 10

Ox: Needs membrane associated complexes, sub needs soluble enzymes
Major process for ATP Synthesis in cells that need lots of energy, sub is minor
NEEDS OXYGEN, sub can happen to some extent without O2
Energy coupling indirectly, subs is directly through formation of high energy of hydrolysis bond

Question 11

Normal Coupling Between Electron Transport and ATP Synthesis

Answer 11

Tightly coupled

Question 12

How is ET and ATP Synthesis tightly coupled?

Answer 12

[ATP]. When high:
ADP levels low so less substrate for ATP synthesis, protons don’t re enter
Proton levels build up very high in inner membrane space so protons can’t be pumped out
ET stops

Question 13

Uncouplers of ET and ATP Synthesis

Answer 13

Dinitrophenol

Question 14

How does Dinitrophenol Uncouple ET and ATP Synthesis

Answer 14

Increases inner mitcochondrial membranes permeability to H+

H+ can pass back into matrix not through ATP synthase

Potential energy from p.m.f dissipated as heat

Question 15

Dinitrophenol danger

Answer 15

Proton leakage generates lots of heat

Question 16

Uncoupling Proteins (UCP)
Functions

Answer 16

Allow leak of protons through inner mitochondrial membrane reducing p.m.f reducing ATP synthesis

Question 17

UCP1 use

Answer 17

In brown adipose tissue
Leads to release of lots of heat to allow for non-shivering thermogenesis

Question 18

What hormone is released in the response to cold

Answer 18

Noradrenaline

Question 19

Noradrenaline use in increasing body temp

Answer 19

Stimulates lypolysis (produces lots of fatty acids)
Fatty acids oxidised forming lots of NADH and FADH2
Increases the p.m.f
But it also stimulates UCP1 so it makes lots of H+ able to dissipate their energy as heat without synthesising ATP

Question 20

Inhibitors of Electron transport

Answer 20

Anaerobic Conditions
CO
Cyanide

NADH and FADH2 can’t be oxidised p.m.f.not created no ATP synthesised