OxPhos reg/ Agbas

Question 1

What are the three goals of OxPhos?

Answer 1

• Transfer electrons
• Establish a proton gradient
• Synthesize ATP

Question 2

What is the chemiosmotic hypothesis?

Answer 2

Energy is generated from creating a proton gradient

Question 3

What two forces constitute the pmf which drives ATP synthesis?

Answer 3

• pH gradient

- Membrane potential

Question 4

What are the 3 postulates of the chemiosmotic theory?

Answer 4

1. mETC translocates e- across inner mm from one rspiratory ecc complex to another
2. ATP Synthase uses pmf to drive phosphorylation of ADP
3. IMM is impermeable to H+/OH-

Question 5

Describe the basic structure of ATP synthase.

Answer 5

• Transmembrane
• Ball and stick shape w/ two subunits
• F0 “stick” intramembrane subunit is proton channel
• F1 subunit is “ball” and contains catalytic domain

Question 6

Describe the structure of the F1 subunit of ATP Synthase

Answer 6

• 5 subunits; a3, B3, y, Delta, and e
• a/B hexameric ring
• a/B bind nucleotides, ONLY B CATALYTIC
• y has long helical coil extending into hexamer

Question 7

What is important regarding the formation of ATP Synthase?

Answer 7

• Form dimers -> form oligomers
• Structure stabilizes rotational forces
• Maintains curvature in inner membrane
• Cristae formed allow close proximity to H+ gradient

Question 8

Why do cristae display a folded structure?

A. To increase SA
B. Increase TCA cycle
C. Form efficient proton gradient in groove
D. Increase ETC reactions

Answer 8

C. Form efficient proton gradient in groove

Question 9

How many Kcal of energy used per mole of ATP formed?

Answer 9

7.3 Kcal/Mol

Question 10

What is oligomycin?

Answer 10

ATPase inhibitor (F0)

Question 11

What constitutes pmf?

A. pH gradient
B. Membrane potential
C. ATP production rate
D. pH gradient and membrane potential
E. ADP concentration

Answer 11

D. pH gradient and membrane potential

Question 12

What is ATP-ADP translocase?

Answer 12

• ATP/ADP not permeable across membrane
• Carries ATP/ADP through outer and inner mito-membranes
• Complex VI

Question 13

How many H+ are needed for ATP synthesis and translocation?

Answer 13

4 H+
3 -> Synthesis
1 -> translocation

Question 14

What are the two shuttle systems for NADH to cross mitochondrial membrane?

Answer 14

Malate -> aspartate shuttle: Oxaloacetate reduced and gets converted to malate and shuttled into mitochondria. Malate transported back as a-ketoglutarate via conversion of aspartate

Glycerophosphate -> FADH2 reduction of Glyceral3P which enters and mitochondria,

Question 15

What is the organ location, generated substrate, and ETC entrance for Malate-aspartate shuttle?

Answer 15

• Heart, Liver, and kidneys
• Generates NADH in matrix
• Enters ETC at Complex I

Question 16

What is the organ location, generated substrate, and ETC entrance for Glycerophosphate shuttle?

Answer 16

• muscle and brain
• generates FADH2 in inner Mitomembrane
• FADH2 joins at CoQ

Question 17

What molecule is regulated by respiratory control (acceptor control)?

Answer 17

ADP

Question 18

Which of the following factors governs the pmf in intact mitochondria?

A. Standard redox potential of intermediates
B. ATP production rate
C. Membrane potential and pH gradient
D. Proton gradient formaiton in intermembrane space

Answer 18

D. Proton gradient formaiton in intermembrane space

Question 19

What are the complex I inhibitors?

Answer 19

Amytal
Rotenone
Myxothiazol
Piericidin A

Question 20

What is/are the complex II inhibitor(s)?

Answer 20

Malonate

Question 21

What is/are the complex II inhibitor(s)?

Answer 21

Antimycin

Question 22

What is/are the Complex IV inhibitor(S)?

Answer 22

CO
Cyanide
H2S

Question 23

How can some organisms generate heat with low ATP synthesis?

Answer 23

• Brown adipose tissue is able to uncouple OxPhos and ATP synthesis.
• IMM contains uncoupling protein (UCP 1 or thermogenin) which transfers protons from cytoplasm to matric
• Energy converted to heat instead of ATP