Week 12

Question 1

What is ATP?

Answer 1

The main energy currency of the cell

Question 2

What type of bond stores energy in ATP?

Answer 2

Phosphoanhydride bonds between phosphate groups

Question 3

What is free energy (ΔG)?

Answer 3

Energy available to do work

Question 4

Is ATP hydrolysis exergonic or endergonic?

Answer 4

Exergonic (releases energy)

Question 5

Why is ATP hydrolysis useful for metabolism?

Answer 5

It can be coupled to drive unfavorable (endergonic) reactions

Question 6

What is reaction coupling?

Answer 6

Using energy from ATP hydrolysis to power another reaction

Question 7

Where is the ETC located?

Answer 7

Inner mitochondrial membrane

Question 8

What is the final electron acceptor in the ETC?

Answer 8

Oxygen (O₂)

Question 9

What is oxygen reduced to?

Answer 9

Water (H₂O)

Question 10

What donates electrons to the ETC?

Answer 10

NADH and FADH₂

Question 11

Which complexes pump protons?

Answer 11

Complex I, III, and IV

Question 12

Which complex does NOT pump protons?

Answer 12

Complex II (succinate dehydrogenase)

Question 13

Mobile electron carriers in ETC?

Answer 13

Coenzyme Q (ubiquinone) and cytochrome c

Question 14

Function of Coenzyme Q?

Answer 14

Transfers electrons from Complex I & II to Complex III

Question 15

Function of cytochrome c?

Answer 15

Transfers electrons from Complex III to Complex IV

Question 16

What is the chemiosmotic (Mitchell) hypothesis?

Answer 16

Proton gradient generated by ETC drives ATP synthesis

Question 17

What two gradients form the proton motive force?

Answer 17

Electrical gradient + pH gradient

Question 18

Where do protons accumulate?

Answer 18

Intermembrane space

Question 19

Where do protons flow back?

Answer 19

Into the mitochondrial matrix

Question 20

What enzyme makes ATP?

Answer 20

ATP synthase (Complex V)

Question 21

Parts of ATP synthase?

Answer 21

F₀ (membrane) and F₁ (matrix)

Question 22

Function of F₀?

Answer 22

Proton channel

Question 23

Function of F₁?

Answer 23

Catalyzes ADP + Pi → ATP

Question 24

How does ATP synthase work?

Answer 24

Proton flow causes rotation → conformational change → ATP synthesis

Question 25

What is respiratory control?

Answer 25

Regulation of ETC activity by ADP availability

Question 26

High ADP causes what effect?

Answer 26

Increased electron transport and ATP synthesis

Question 27

Low ADP causes what effect?

Answer 27

Slowed respiration and ATP production

Question 28

Why are electron shuttles needed?

Answer 28

NADH cannot cross the inner mitochondrial membrane

Question 29

Two main shuttles?

Answer 29

Glycerol phosphate shuttle & Malate-aspartate shuttle

Question 30

Glycerol phosphate shuttle transfers electrons to which molecule?

Answer 30

FAD → FADH₂

Question 31

ATP yield of glycerol phosphate shuttle per NADH?

Answer 31

~1.5 ATP

Question 32

Malate-aspartate shuttle transfers electrons to which molecule?

Answer 32

NAD⁺ → NADH

Question 33

ATP yield of malate-aspartate shuttle per NADH?

Answer 33

~2.5 ATP

Question 34

Which tissues mainly use malate-aspartate shuttle?

Answer 34

Liver, heart, kidney

Question 35

Which tissues mainly use glycerol phosphate shuttle?

Answer 35

Brain and skeletal muscle

Question 36

Rotenone inhibits which complex?

Answer 36

Complex I

Question 37

Antimycin A inhibits which complex?

Answer 37

Complex III

Question 38

Cyanide inhibits which complex?

Answer 38

Complex IV

Question 39

Carbon monoxide inhibits which complex?

Answer 39

Complex IV

Question 40

Effect of ETC inhibitors?

Answer 40

Block ATP synthesis → cell death

Question 41

Example of ATP synthase inhibitor?

Answer 41

Oligomycin

Question 42

How does oligomycin act?

Answer 42

Blocks proton channel in F₀ subunit

Question 43

Result of oligomycin?

Answer 43

Stops ATP synthesis and electron transport

Question 44

What is an uncoupler?

Answer 44

Substance that dissipates proton gradient without making ATP

Question 45

Example of chemical uncoupler?

Answer 45

2,4-dinitrophenol (DNP)

Question 46

Effect of uncouplers?

Answer 46

Heat production instead of ATP

Question 47

What is UCP1 (thermogenin)?

Answer 47

Uncoupling protein in brown fat

Question 48

Function of UCP1?

Answer 48

Non-shivering thermogenesis

Question 49

High-dose aspirin causes what effect on mitochondria?

Answer 49

Uncoupling → hyperthermia

Question 50

What are ROS?

Answer 50

Partially reduced oxygen species

Question 51

Examples of ROS?

Answer 51

Superoxide, hydrogen peroxide, hydroxyl radical

Question 52

Enzymes that protect against ROS?

Answer 52

Superoxide dismutase, catalase, glutathione peroxidase

Question 53

Why are brain and muscle sensitive to ETC defects?

Answer 53

They require large amounts of ATP

Question 54

What happens when oxidative phosphorylation fails?

Answer 54

↓ ATP → organ failure → death

Question 55

Mitochondrial dysfunction is associated with what diseases?

Answer 55

Neuromuscular disorders, neurodegeneration, metabolic diseases