Oxidative Phosphorylation II

Question 1

The catalytic domain, which binds ADP and Pi and catalyzes the reaction to form ATP

Answer 1

The F1 part of ATP synthase

Question 2

A molecule which binds to the Fo portion of ATP synthase. It blocks the proton pathway in Fo, and prevents the reentry of protons into the matrix of the mitochondria

Answer 2

Oligomycin

Question 3

Oligomycin prevents

Answer 3

ATP synthesis

Question 4

During the normal tight coupling of electron transport and ATP formation, the inhibition of ATP formation will also prevent the

Answer 4

Oxidation-reduction reactions

Question 5

What are two inhibitors of Complex I?

Answer 5

Amytal and Rotenone

Question 6

What is an inhibitor of complex III?

Answer 6

Antimycin A

Question 7

What are three inhibitors of complex IV?

Answer 7

Cyanide, CO, and sodium azide

Question 8

Electrons will build up on the substrate side of the inhibited complex, making all components 100%

Answer 8

Reduced

Question 9

All electron transport chain components on the oxygen side of the inhibitor blockage will be 100%

Answer 9

Oxidized

Question 10

Binds to the oxidized form of the heme iron in cytochrome a3, and keeps this cytochrome permanently in its oxidized form

Answer 10

Cyanide (CN)

Question 11

With Cyanide poisoning, complex IV can never be reduced by

Answer 11

Cytochrome C

Question 12

Lethal because it blocks all ATP formation

Answer 12

Cyanide poisoning

Question 13

Has a very high affinity for cyanide (again it is the oxidized heme iron)

Answer 13

MetHb

Question 14

So if a person has gotten CN poisoning, the goal is to convert about 20-25% of their hemoglobin to

Answer 14

MetHb

Question 15

This MetHb will bind tightly to any free CN ions in the

Answer 15

Blood

Question 16

Starts the conversion of Hb to MetHb

Answer 16

Sodium nitrate

Question 17

The CNMetHb can be converted to thiocyanite after the addition of

Answer 17

Na-thiosulfate

Question 18

Usually the rate of electron transport (or respiration) is tightly coupled to our bodies

Answer 18

ATP needs

Question 19

When ATP levels are high, the rate of electron transport

Answer 19

Slows down

Question 20

When ATP levels are low (and ADP levels high), the rate of electron transport speeds up, to quickly make more

Answer 20

ATP

Question 21

However, there are compounds which uncouple electron transport from ATP formation. When uncoupling occurs, the respiration rate is very fast, but

Answer 21

No ATP is made

Question 22

When there is no ATP being formed, all of the energy from the oxidation reduction reactions of electron transport goes into

Answer 22

Heat

Question 23

Uncouplers make the inner mitochondrial membrane “permeable” to

Answer 23

Protons

Question 24

Usually, the rate of electron transport is limited by the creation and dissipation of the proton gradient. In the presence of an uncoupler, the oxidation-reduction reactions keep going very fast and keep pumping out protons, but a gradient is

Answer 24

Never formed

Question 25

The net result is that respiration continues at a maximal rate, limited only by the supply of

Answer 25

NADH and FADH2

Question 26

In the 1990’s, natural uncoupling proteins (UCP) were discovered in small mammals in a specialized tissue known as

Answer 26

Brown Adipose Tissue (BAT)

Question 27

This tissue is brown because of the high concentration of

Answer 27

Mitochondria and vascularization

Question 28

The biological role of BAT is

Answer 28

Heat production

Question 29

Associated with heat production in brown adipose tissue

Answer 29

UCP1 (thermogenin)

Question 30

The major function of brown adipose tissue is

Answer 30

Nonshivering thermogenesis

Question 31

In response to cold, sympathetic nerve endings release norepinephrine, which activates a lipase in brown adipose tissue that releases fatty acids from

Answer 31

Triacylglycerols

Question 32

Fatty acids serve as a fuel for the tissue and participate directly in the proton conductance channel by activating

Answer 32

UCP1

Question 33

When UCP1 is activated by fatty acids, it transports protons from the cytosolic side of the inner mitochondrial membrane back into the mitochondrial matrix without

Answer 33

ATP generation

Question 34

Thus, it partially uncouples oxidative phosphorylation and generates additional

Answer 34

Heat

Question 35

Inhibitors bind to a component of the electron transport chain, stop the oxidation-reduction reactions; no electron transport; no ATP formation. These inhibitors are

Answer 35

CN, Antimycin A, Rotenone

Question 36

Allows protons to pass freely through the inner mitochondrial membrane, so a proton gradient cannot be built up

Answer 36

Uncouplers