Mitochondrial Bioenergetics

Question 1

Pyruvate enters mitochondria through what carrier?

Answer 1

Mitochondrial pyruvate carrier

Question 2

PDC is active in what form?

Answer 2

Dephosphroylated

Question 3

Inhibitors of PDH/PDC?

Answer 3

Acetyl CoA (E1 subunit), High ATP and high NADH

Question 4

Activators of PDH/PDC?

Answer 4

High AMP, Pyruvate, NAD+, Ca2+, Mg2+

Question 5

Irreversible steps of TCA?

Answer 5

Steps: 1, 3, and 4.

1. ) OAA -> Citrate via citrate synthase
2. ) Isocitrate -> Ō ketoglutarate via Isocitrate dehydrogenase
3. ) å ketoglutarate -> succinyl CoA via å ketoglutarate dehyrdogenase

Question 6

Products of TCA cycle?

Answer 6

3 NADH = 2.5 ATP
1 FADH2 = 1.5 ATP
1 GTP = 1 ATP
CO2 is byproduct

Question 7

Steps that produce NADH?

Answer 7

Isocitrate -> å ketoglutarate
å ketoglutarate -> succinyl CoA
Malate -> OAA

Question 8

Steps that produce FADH2?

Answer 8

Succinate -> Fumarate via Succinate dehydrogenase

Question 9

Steps that produce GTP?

Answer 9

Succinyl CoA -> Succinate via Succinate thiokinase

Question 10

Rate limiting step of TCA? Activators? Inhibitors?

Answer 10

Isocitrate dehydrogenase. Activators are Isocitrate, ADP, and Ca2+. Inhibitors are NADH and ATP.

Question 11

Why isn TCA anaplerotic?

Answer 11

Anaplerotic rxns provide intermediates for replenishing TCA cycle => degradation of AA and Carboxylation of pyruvate.

Question 12

Which of the following best explains the function of TCA?

Answer 12

It participates in the synthesis of glucose to pyruvic acid?

Question 13

2-oxoglutaric aciduria

Answer 13

rare disorder with developmental delay and neurological problems in infants. Metabolic acidosis, microcephaly, mental retardation

Question 14

Fumarase deficiency

Answer 14

Fatal outcome w/in 2 yrs of life.Encephalomyopathy, dystonia, increased urinary excretion, AR disorder.

Question 15

Successful OxPhos must accomplish the following key goals:

Answer 15

1. ) Transfer e- from NADH and FADH2 -> O2
2. ) Establish a proton gradient
3. ) synthesize ATP

Question 16

Chemiosmotic hypothesis

Answer 16

Electrons are pumped from matrix to inner mitochondrial space

Question 17

Two factors that constitute a proton motive force?

Answer 17

pH gradient and membrane potential

Question 18

Inhibitors of ATP synthase (Complex V)

Answer 18

Oligomycin disrupts proton transport through the channel

Question 19

Mobile carriers of ETC?

Answer 19

CoQ (ubiquinone) and Cytochrome C

Question 20

Antimycin inhibits….

Answer 20

Complex III

Question 21

Uncoupling mechanism and example

Answer 21

DNP -> Protons reenter the mitomatrix from the innerrmembrane space: TCA cycle and e- transfer to O2 are accelerated, ATP synthase is inhibited, and Heat is generated.

Question 22

Which would not occur upon treatment of DNP to mitochondria ?

Answer 22

Increase in the P/O ratio?

Question 23

2 shuttle systems to transfer NADH across mitomembrane and where they place:

Answer 23

1. ) malate-aspartate shuttle -> heart, liver, and kidney

2. ) Glycerophosphate shuttle -> Brand and skeletal muscle