Lecture 4 - Oxidative Phosphorylation and Mitochondrial Function Flashcards Preview

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Flashcards in Lecture 4 - Oxidative Phosphorylation and Mitochondrial Function Deck (34)
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1

Most of the energy derived from food originates in electron pairs that are found in chemical bonds. ___________ reactions result in the loss of the electrons from cellular metabolites with the concomitant release of energy that is trapped ultimately in the form of ATP.

Oxidation

2

Adenylate kinase catalyzes the conversion of 2 ADP to ATP and AMP. Where in the mitochondria is this enzyme found?

Intermembrane space

3

One particular enzyme that is found in the mitochondrion intermembrane space catalyzes the conversion of Creatine + ATP to Creatine-P + ADP. What enzyme is being described?

Creatine kinase

4

Which enzyme is NOT associated with the inner membrane of the mitochondria?

A. Succinate dehydrogenase
B. Adenine nucleotide translocase
C. Pi transporter
D. Respiratory chain proteins
E. Glutamate dehydrogenase
F. ATP synthetase

E - Glutamate dehydrogenase is associated with the mitochondrial matrix.

5

Which enzyme is NOT associated with the mitochondrial matrix?

A. Enzymes of the TCA cycle
B. Enzymes for B-oxidation of fatty acids
C. a-glycerol-P dehydrogenase
D. Pyruvate dehydrogenase complex
E. Branched chain amino acid dehydrogenase complex

C. a-glycerol-P dehydrogenase is associated with the inner membrane of the mitochondria

6

The function of the electron transport chain (respiratory chain) is to:

collect and oxidize NADH and FADH2 from various sources

7

The 5 major components of the electron transport chain are the enzymes and coenzymes involved in handling electrons, including:

1. NAD-linked dehydrogenases
2. Flavoproteins
3. Iron-sulfur proteins
4. Coenzyme Q
5. Cytochromes

8

Which multienzyme complex of the ETC does NOT pump H+ out of the matrix?

A. Complex I
B. Complex II
C. Complex III
D. Complex IV

B - electrons are passed, but not H+ is pumped by Complex II.

9

The number of H+ pumped due to NADH is _______ than H+ pumped due to FADH2 entering through Complex II.

greater (electrons are passed, but no H+ is pumped by Complex II)

10

Electrons derived from the B-oxidation of fatty acids bypass both Complex I and Complex II and are directly passed to:

CoQ

11

Complex I of the ETC accepts electrons from ___________ and passes them along to CoQ.

mitochondrial NADH

12

Complex II is the same as the succinate dehydrogenase of the TCA cycle. It passes electrons from succinate through _______ and an iron-sulfur center to CoQ.

FADH2

13

Electrons are transferred from Complex III to Complex IV via _______, a mobile component of the chain.

cyt c

14

Complex III is composed of two cytochromes. What are they?

1. cyt. b
2. cyt c1

15

Arrangement of the components in the respiratory chain is from _______ to _______.

electropositive (best e- donor) to electronegative (best e- acceptor)

16

The transfer of electrons from a donor to oxygen is associated with the formation of _________ and ______.

a proton gradient and membrane potential

17

What are the 3 subunits of ATP synthase?

1. F1 domain
2. Fo domain
3. Stalk proteins

18

What process releases the energy associated with the proton gradient that is generated by the ETC?

the flow of protons back through the Fo channel into the matrix

19

How is P/O ratio defined?

The number of inorganic phosphate groups incorporated into ATP per atom of molecular oxygen consumed

20

Oxidation of ____________ substrates have a P/O ratio of 2.5.

A. FAD-linked
B. NAD-linked
C. Reduced ascorbate
D. None of these are correct

B - electrons from NADH pass through all 3 of the complexes in the electron transport chain that act as pump protons

21

Oxidation of ____________ substrates have a P/O rationof 1.5.

A. FAD-linked
B. NAD-linked
C. Reduced ascorbate
D. None of these are correct

A - these electrons bypass Complex I

22

Oxidation of ____________ substrates have a P/O ratio of 1.

A. FAD-linked
B. NAD-linked
C. Reduced ascorbate
D. None of these are correct

C - this directly reduces cytochrome c, bypassing Complex I and III

23

The presence of an uncoupling protein, ___________, uncouples oxidation and phosphorylation and is found in the inner mitochondrial membrane of brown fat.

UCP1; thermogenin

Note: this process is important in warming the blood of newborns.

24

Azide, carbon monoxide, and cyanide are classified as site-specific inhibitors of ATP synthesis because they:

A. directly block phosphorylation at the Fo channel
B. bind to Complex I in the ETC
C. make the mitochondrial membrane abnormally permeable to protons, dissociating oxidation from phosphorylation
D. bind to Complex IV in the ETC

D - site-specific inhibitors block e- transfer by binding to a particular component of the ETC

25

Oligomycin is classified as an inhibitor of Complex V (ATP Synthase) because it:

A. directly block phosphorylation at the Fo channel
B. bind to Complex I in the ETC
C. make the mitochondrial membrane abnormally permeable to protons, dissociating oxidation from phosphorylation
D. bind to Complex IV in the ETC

A - oligomycin prevents the return flow of protons through the Fo channel into the mitochondrial matrix

26

Which of the following is NOT classified as an "uncoupler" inhibitor of mitochondrial ATP synthesis?

A. Ionophores
B. Uncoupling proteins
C. Dinitrophenol
D. Amytal
E. Very high thyroid hormone

D - this is a site-specific inhibitor that binds to Complex I of the ETC

27

Uncouplers dissociate _______ from _________ by making the mitochondrial membrane abnormally permeable to protons.

oxidation from phosphorylation

28

Since there is no transport protein for NADH, a ____________ is used to get reducing equivalents from cytosolic NADH into the mitochondria.

shuttle system

29

The net effect of the glycerol phosphate shuttle is to use cytosolic NADH to generate mitochondrial FADH2. This shuttle is enriched in:

brain and fast-contracting skeletal muscle

30

The net efffect of the malate shuttle is to convert cytosolic NADH to mitochondrial NADH. This shuttle is particularly enriched in:

liver and cardiac muscle