L6 - ETC and Oxidative Phosphorylation

Question 1

Which complex allows hydrogens back into the inner mitochondrial matrix?

Answer 1

Complex V

Question 2

What side effect do uncoupling proteins have and what causes it?

Answer 2

heat generation through increased ETC/O2 consumption

Question 3

Which substance inhibits ATP synthase?

Answer 3

oligomycin

Question 4

Complex V can also be called?

Answer 4

F0F1-ATP synthase

Question 5

What three substances inhibit NADH DHG?

Answer 5

1) rotenone
2) piericidin A
3) amytal

Question 6

What are the other names for Complex III and IV?

Answer 6

Complex III: cytochrome c reductase

Complex IV: cytochrome c oxidase

Question 7

What are the four molecules which bind and inhibit cytochrome oxidase (Complex IV)?

Answer 7

1) CO
2) azide
3) H2S
4) cyanide (CN-)

Question 8

What does Complex I consist of? What does Complex II consist of?

Answer 8

Complex I: NADH DHG, FMN, FeS

Complex II: Succinate DHG, FAD, FeS

Question 9

Where is thermogenin found? What is its physiological function?

Answer 9

brown adipose tissue; generates heat

Question 10

Which complexes in the ETC contribute to the hydrogen ion gradient?

Answer 10

Complex I, III, and IV

Question 11

Where does ATP stand in terms of free energy as compared to low and high-energy organic phosphate compounds?

Answer 11

somewhere in the middle

Question 12

Which molecule do complexes I and II give their electrons to?

Answer 12

CoQ (ubiquinone)

Question 13

What are the two mobile electron transferring compounds in the ETC?

Answer 13

cytochrome c and CoQ

Question 14

Which molecule is oxidized by complex II and which molecule does it form?

Answer 14

Succinate is oxidized to fumarate

Question 15

Which complex does CoQ donate its electrons to?

Answer 15

Complex III

Question 16

What are three high-energy compounds?

Answer 16

1) phosphocreatine
2) 1,3-bisphosphoglycerate
3) PEP

Question 17

What are the prosthetic groups for each of the complexes I through IV?

Answer 17

I - FMN
II - FAD
III - heme
IV - copper and heme

Question 18

Are NADH and FADH2 oxidized or reduced to produce electrons that are transferred to the ETC?

Answer 18

oxidized

Question 19

What two very legal and very cool substances inhibit ADP/ATP translocase?

Answer 19

1) atractyloside

2) bongkrekic acid

Question 20

How do uncoupling substances work?

Answer 20

Open up holes in the inner mitochondrial membrane which provide a conduit for hydrogen ions to flow down their concentration gradient thus bypassing ATP synthesis

Question 21

Antimycin A inhibits which enzyme?

Answer 21

cytochrome reductase or complex III

Question 22

What are two examples of ionophores?

Answer 22

1) gramicidin

2) valinomycin

Question 23

The antiporter which transports ATP and ADP between the inner membrane of mitochondria is also called?

Answer 23

Adenine nucleotide translocase

Question 24

How does ADP enter the mitochondrial matrix?

Answer 24

Is shipped in for ATP by ADP/ATP antiporter

Question 25

What are four major uncouplers of oxidative phosphorylation?

Answer 25

1) thermogenin
2) DNP (dinitrophenol or 2,4-dinitrophenol)
3) ionophores
4) aspirin

Question 26

Where do hydrogens accumulate when pumped out by ETC proteins?

Answer 26

intermembranous space

Question 27

Which part of complex V is a port for hydrogens? Which synthesizes ATP?

Answer 27

F0 - H+ port

F1 - ATP synthase

Question 28

How does adenine nucleotide translocase provide electroneutrality between its transport of ATP and ADP?

Answer 28

Symport of phosphate and hydrogen

Question 29

What are ionophores? What do they increase?

Answer 29

Ionophores are mostly membrane channels that increase proton permeability

Question 30

How many “high-energy” bonds does ATP have? What types of bonds are these?

Answer 30

1) two

2) phosphodiester