Cell Integrity

Question 1

Lack of oxygen

Answer 1

Hypoxia = diminished
Anoxia = complete loss

Leads to oxidative phosphorylation failure

Question 2

Substrate level phosphorylation

Answer 2

Direct transfer of high energy phosphate group from intermediate substrate to ADP

Question 3

Oxidative phosphorylation

Answer 3

ATP made using energy derived from transfer of electrons in electron transport system

(In mitochondria)

Question 4

Energy and OxPhos

Answer 4

NADH reduction = -220kJ/mol
FADH2 reduction = -167kJ/mol

Delta G for ATP = -31 kJ/mol so energy released from cofactor reduction able to make many phosphoanhydride bonds

Question 5

Electron transport chain

Answer 5

Complex 1 - NADH dehydrogenase
Complex 2 - Succinate dehydrogenase

Coenzyme Q

Complex 3 - Q cytochrome C oxidoreductase

Cytochrome C

Complex 4 - Cytochrome C oxidoreductase

Question 6

ATP synthase subunits

Answer 6

F0 - membrane bound (abc subunits)
F1 - projects into matrix (bag subunits)

Question 7

How does atp synthase work

Answer 7

H+ travel through along concentration gradient back into matrix through F0
F1 rotates - generates energy for ADP + Pi => ATP

rotating other way = hydrolysis

Question 8

Why does FADH2 make less ATP

Answer 8

Succinate dehydrogenase = part of TCA - doesn’t pump H+ across (enzyme, not channel)
As NADH dehydrogenase is bypassed, less H+ grad made so less ATP made at end than NADH

Question 9

Metabolic poisons

Answer 9

Rotenone - Complex 1
Malonate - Complex 2
CN + N3 - Complex 4

DNP - shuttles H+ back into matrix - increases metabolic activity
Oligomycin - inhibits ATP synthase

Question 10

Reducing vs oxidating substrate

Answer 10

Reducing = oxidised = donates electrons
Oxidising = reduced =accepts electrons

Question 11

Redox couple definition + examples

Answer 11

Substrate that can exist in reduced or oxidised form

NAD/NADH, FAD/FADH2, O2/H2O, Fe3+/2+

Question 12

Redox potential

Answer 12

Ability of redox couple to accept or donate electrons

Question 13

How is standard redox potential measured

Answer 13

Using hydrogen electrode as a reference (E0)

Question 14

Positive vs negative E0

Answer 14

Neg = tendency to donate e- so more reducing power than H

Pos = tendency to accept e- so less reducing power than H

Question 15

E0 along ETC

Answer 15

Along ETC, channels, Q + CC = more positive E0 so have more affinity for electrons so ETC movement is energetically favourable