Topic 3: Oxidative Phosphorylation (ETC)

Question 1

What parts of the ETC are soluble?

Answer 1

CoQ and Cyt C

Question 2

What’s another name for Complex 1?

Answer 2

NADH-Q Reductase

Question 3

What’s another name for Complex 2?

Answer 3

Succinate Dehydrogenase or FADH2-Q Dehydrogenase

Question 4

What’s another name for Complex 3?

Answer 4

Cytochrome reductase

Question 5

What’s another name for Complex 4?

Answer 5

Cytochrome oxidase

Question 6

What’s another name for Complex 5?

Answer 6

ATP Synthase

Question 7

What is the final electron acceptor in the ETC?

Answer 7

Oxygen –> Makes water

Question 8

Can the complexes move throughout the membrane at will?

Answer 8

No the Complexes are fixed. Cyt C and CoQ are soluble and can move.

Question 9

Describe what happens to NADH when it encounters the ETC.

Answer 9

Complex 1 H+ is removed into the matrix and NAD+ is regenerated while e- continues through the chain–> CoQ –> Complex 3 –> Complex 4 –> Complex 5

The e- moving from complex to complex provides energy for H+’s to be pumped out along the way.

Question 10

Describe what happens to FADH2 when it encounters the ETC.

Answer 10

Complex 2 H+ is removed in the matrix and FAD+ is regenerated while takes e- continues through the chain–> CoQ –> Complex 3 –> Complex 4 –> Complex 5

The e- moving from complex to complex provides energy for H+’s to be pumped out along the way.

Question 11

How many ATP are generated per NADH?

Answer 11

2.5 because they enter at Complex 1

Question 12

How many ATP are generated per FADH2?

Answer 12

1.5 because they enter at Complex 2

Question 13

Name a couple substances that inhibit Complex 1.

Answer 13

Rotenone (used as fish poison) and Amytal (barbiturate anesthetic)

Question 14

Name a few substances that inhibit Complex 3.

Answer 14

Antifungals: Antimycin A, Myxothiazol, Stigmatellin

Question 15

Name a few substances that inhibit Complex 4.

Answer 15

Inorganic molecules: Cyanide, Carbon Monoxide, Sodium azide (antibacterial/antifungal)

Question 16

What is the Triple Chemiosmotic Gradient?

Answer 16

CONCENTRATION of H+, CHARGE difference established by that, and OSMOTIC pressure as well

Question 17

How many protons/H+ are pumped out per NADH?

Answer 17

10: 4 at Complex 1; 2 at Complex 3; 4 at Complex 4

Question 18

How many protons/H+ are pumped out per FADH2?

Answer 18

6: 2 at Complex 3; 4 at Complex 4

Question 19

How many protons are required for Complex 5/ATP Synthase to generate ATP?

Answer 19

4 Protons per ATP

Question 20

How many ATP are generated per NADH?

Answer 20

10 protons per molecule/4 protons per ATP = 2.5 ATP per NADH

Question 21

How many ATP are generated per FADH2?

Answer 21

6 protons per molecule/4 protons per ATP = 1.5 ATP per FADH2

Question 22

What does Cold Stress stimulate?

Answer 22

Release of Thyroxine which Uncouples the ETC via thermogenin. This is a natural occurrence of uncoupling.

Also, sympathetic release of NorEpinephrine which also activates thermogenin via increased FFA in fat cells.

Question 23

What is UCP1?

Answer 23

Thermogenin. It is a normal physiological uncoupler of oxidative phosphorylation.

Question 24

When would you benefit from uncoupling oxidative phosphorylation?

Answer 24

Newborns, hibernating animals, cold adapted animals

Question 25

Are mitochondrial disease compatible with life?

Answer 25

Nope

Question 26

Why would you see heat-seeking in a hypothyroid dog?

Answer 26

Lack of thyroxine leads to insufficient response to cold stress –> animal is cold, wants to warm up = heat-seaking