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(OMS1) SFM Exam 1 > Lecture 4: Mitochondrial Bioenergetics > Flashcards

Lecture 4: Mitochondrial Bioenergetics Flashcards

1
Q

What is substrate level phosphorylation? What are some examples?

A

Direct transfer of a phosphate group to ADP or GDP

PEP –> Pyruvate
Phosphocreatine –> Creatine (MI marker)

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2
Q

What is oxidative phosphorylation?

A

ATP formation as a result of the transfer of electrons from NADH or FADH 2 to oxygen by a series of electron carriers

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3
Q

What are amphibolic reactions?

A

Anabolic (making bigger things) and catabolic (breaking down things)

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4
Q

Where does the TCA cycle take place?

A

Mitochondrial matrix

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5
Q

How does pyruvate enter mitochondria?

A

Mitochondrial Pyruvate Carrier (MPC)

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6
Q

What downregulates pyruvate dehydrogenase complex (PDC)?

A

NADH, ATP, Acetyl-CoA

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7
Q

Which three steps of the TCA cycle are irreversible and regulatory? What enzymes catalyze them?

A

Step 1: Citrate Synthase
Step 3: Isocitrate dehydrogenase (rate limiting)
Step 4: α-Ketoglutarate Dehydrogenase

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8
Q

What are the four products of the TCA cycle?

A

1 FADH2
3 NADH
1 GTP
2 CO2

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9
Q

What enzyme can hijack the TCA cycle from the start, and what inhibits it to allow the TCA cycle to continue?

A

Pyruvate Carboxylase (pyruvate –> oxaloacetate). Oxaloacetate will then enter gluconeogenesis

Insulin inhibits Pyruvate Carboxylase

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10
Q

What TCA intermediate can be shunted off to make porphyrins like heme?

A

Succinyl CoA

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11
Q

What are the clinical effects of phosphatase deficiency?

A

Lactic Acidosis

When PDC is phosphorylated, it is inactive. Pyruvate Dehydrogenase Phosphatase activates PDC.
When PDC is not activated, pyruvate will produce lactate instead of Acetyl Co-A.

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12
Q

At what part of Pyruvate Dehydrogenase Complex do low energy compunds push the reaction forward?

A

At Pyruvate Kinase

Low energy compounds STOP pyruvate kinase from phosphorylating Pyruvate Dehydrogenase

Goal: Keep PDC activated (dephosphorylated)

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13
Q

What 4 TCA enzymes produce reducing power?

A

isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase
succinate dehydrogenase
malate dehydrogenase

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14
Q

Which TCA cycle enzyme produces FADH2?

A

Succinate Dehydrogenase

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15
Q

What is 2-oxoglutaric aciduria?

A

Rare disorder with severe neurological and developmental problems in infants

  • metabolic acidosis
  • severe microcephaly
  • mental reatrdation
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16
Q

What is fumarase deficiency?

A

Severe neurologic impairment and infant fatality

17
Q

What is Succinyl-CoA syntetase deficiency?

A

Mutations in enzyme: SUCLA2 and SUCLG1

18
Q

What happens in mitochondrial depletion syndrome?

A

Profound hypotonia
Progressive dystonia
Muscular Atrophy
Hearing impairment

19
Q

Where does oxidative phosphorylation occur?

A

Inner mitochondrial membrane

20
Q

What is mitochondrial fission?

A

Mitochondria divides to make 2 sister mitochondria

21
Q

What is mitochondrial fusion?

A

2 mitochondria fuse to make one

22
Q

Does an agent with a lower Eo’ have a higher or lower affinity for electrons?

A

Eo’ being low means its affinity for electrons is low.

-Normally will be reducing agent (is oxidized)

23
Q

What compounds inhibit Complex 1?

A

Amytal
Rotenone
Myxothiazol
Piericidin A

24
Q

What compound inhibits complex II?

A

Malonate

25
Q

What compound inhibits complex III?

A

Antimycin

26
Q

What three compounds inhibit complex 4?

A

CO (carbon monoxide poisoning)
Cyanide
H2S

27
Q

What inhibits protein pump?

A

Oligomycin

28
Q

What is released when uncoupling happens in the mitochondria?

A

Heat

29
Q

What do you use to measure the efficiency of oxidative phosphorylation?

A

P:O ratio

-Ideal: 3:2

30
Q

What adipose tissue is utilized for uncoupling?

A

Brown Adipose Tissue

31
Q

What complex accepts NADH?

A

Complex I

32
Q

What complex accepts FADH2?

A

Complex II

33
Q

What does Malate-Aspartate shuttle do?

A

Carry NADH across mitochondrial membrane to ETC in complex I
-heart, liver, kidneys

34
Q

What does Glycerophosphate shuttle do?

A

Carry FADH2 to ETC at CoQ

-skeletal muscle and brain

35
Q

What is an indicator of mitochondrial damage (in research?)

A

Cytochrome C levels

(Perepheral membrane protien of the inner mitochondrial membrane)

Shows if the mitochondria is leaking.

36
Q

What are the five coenzymes for PDC?

A 
thiamine pyrophosphate
lipoic acid
FAD
NAD+
CoA
37
Q

What can inhibit PDC?

A

Arsenite

38
Q

What two factors contribute to the proton-motor force to drive ATP synthesis?

A
  1. Membrane potential across inner mitochondrial membrane

2. pH in inter-membrane space

(OMS1) SFM Exam 1 (11 decks)

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