Electron Transport Chain

Question 1

ETC Outline

Answer 1

Final common pathway for electron carriers. Electrons pass down through protein carriers, releasing energy to form ATP from ADP and Phosphate (excess used in thermogenesis and Ca2+ transport).

Question 2

where does glycolysis take place

Answer 2

Cell cytosol

Question 3

Where does TCA cycle take place

Answer 3

Mitochondrial matrix (except for succinct dehydrogenase in membrane)

Question 4

Transport of Molecules between cytosol and matrix

Answer 4

Substrate shuttles (transport proteins). Only carries electrons from cytosolic NADH (rebinds to NAD+ in matrix)

Question 5

Glycerol-3-phosphate Shuttle Outline

Answer 5

Transfer of electrons from cytosolic NADH to matrix FAD

Question 6

Malate-Aspirin Shuttle Outline

Answer 6

Transfer of electrons from cytosol NADH to matrix NAD+

Question 7

Complex 1 Outline

Answer 7

NADH - Ubiquinoine oxireductase. Transfers electrons and proton from NADH to CoQ. Site of proton NADH pumping

Question 8

Complex 2 Outline

Answer 8

Succinate Dehydrogenase. FAHH2 Transfers electrons from succinate to Co Q. Site of proton FADH2 pumping

Question 9

Complex 3 Outline

Answer 9

Transfers electrons from Co Q and Cytochrome C

Question 10

Complex 4 Outline

Answer 10

Electron transfer from cytochrome C to Oxygen

Question 11

Number of NADH pumps

Answer 11

3. Produce 3 ATP

Question 12

Number of FADH2 pumps

Answer 12

2. Produce 2 ATP

Question 13

What gives electron carriers good affinity for electrons

Answer 13

Iron, Iron-sulfur and copper molecules attached. Fe3+ reduced to Fe2+ and reoxidised

Question 14

Purpose of H+ conc gradient across mitochondrial matrix and membrane

Answer 14

Energy created from H+ moving down conc gradient through complex 5 produces ATP

Question 15

Chemiosmotic Hypothesis Outline

Answer 15

Protons pumped (via 3 complexes of ETC) from membrane to inter membrane space (inner membrane is impermeable so H+ is trapped). The proton gradient is used to form ATP

Question 16

ETC Complex 5 (F0 Unit) Outline

Answer 16

Integral membrane protein, H+ channel. Attached to ATP synthase (F1 unit). H+ moving through F0 causes confirmational change (rotation) resulting in F1 forming ATP out of ADP + P

Question 17

Result of protein uncoupling in ETC

Answer 17

Transporters breakdown, H+ gradient isn’t formed. ATP isn’t formed, heat is formed instead (protein: thermogenin, found in brown fat)

Question 18

Synthetic Uncouplers Outline

Answer 18

Drugs that increase the permeability of the inner-mitochondrial membrane (preventing H+ gradient forming). No ATP synthesis, heat synthesised (presents as fever). Eg aspirin overdose

Question 19

Endogenous Uncouplers Outline

Answer 19

Compounds that increase permeability of inner mitochondrial membrane eg excess bilirubin (kernicterus) , uncouples electron oxidative-phosphorylation

Question 20

Mitochondrial/OXPHOS Diseases

Answer 20

Defects in oxidative phosphorylation in ETC proteins due to mutations in mtDNA or nuclear DNA. Eg Parkison’s, Alzhimer’s

Question 21

Heteroplasmy Def

Answer 21

Some DNA is mutated

Question 22

Leber Hereditary Optic Neuropathy

Answer 22

Heteroplasmy, point mutations of mitochondrial components of ETC. Results in sudden onset blindness in young adults as optic nerve has high energy demand and oxidative phosphorylation is impaired

Question 23

Result of any 1 complex in ETC being inhibited

Answer 23

ATP inhibition and cell death

Question 24

Causes of complex inhibition

Answer 24

Iron deficency, riboflavin deficeny (complexes 1 and 2), cyanide (complex 4) and carbon monoxide (complex 4)

Question 25

NAD Coenzyme

Answer 25

Niacin (B3)

Question 26

FAD Coenzyme

Answer 26

Flavin (B2)