Quiz 1 (Bioenergetics) Flashcards Preview

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Flashcards in Quiz 1 (Bioenergetics) Deck (28)
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1
Q

The TCA cycle is an ___ pathway and takes place in the ___.

A

amphibolic / mitochondria

*both catabolic and anabolic

2
Q

What enzyme allows pyruvate to enter the mitochondrial matrix?

What enzyme splits pyruvate into acetyl-CoA?

A

Mitochondrial Pyruvate Carrier (MPC)

Pyruvate Dehydrogenase (PDC)

3
Q

PDC produces…

A

1 NADH / 1 carbon dioxide / 1 acetylene-CoA

4
Q

What enzyme links glycolysis to the TCA Cycle?

A

Pyruvate Dehydrogenase Complex (PDC)

5
Q

PDC is made of:

A

3 enzymes (E1 / E2 / E3)

+

5 coenzymes (TPP / CoA / Lipoic Acid / FAD / NAD+)

  • TPP is derived from Vitamin B1
  • FAD is derived from Vitamin B2
  • NAD+ is derived from Vitamin B3
  • CoA is derived from Vitamin B5
6
Q

Phosphorylation of the PDC occurs in coenzyme ____ of the enzyme ___.

A

Thiamine Pyrophosphate (TPP)

E1

7
Q

PDC regulation:

A

Pyruvate Dehydrogenase Kinase (PDK) =>
+Po = inactive PDC

Pyruvate Dehydrogenase Phosphatase (PDP) =>
-Po = ACTIVE PDC

  • insulin activates PDK
  • activators = Calcium / Magnesium / ADP / CoA / NAD+ / pyruvate
  • inhibitors = Acetyl-CoA / NADH / ATP / Arsenite
8
Q

When ___ phosphorylates PDC, PDC will become ___.

A

PDK / inactive

9
Q

What 3 enzymes are associated with highly regulates steps in the TCA cycle?

A

Citrate Synthase

Isocitrate Dehydrogenase

Alpha-ketoglutarate Dehydrogenase

10
Q

What enzyme is responsible for generation of an ATP equivalent in the TCA cycle?

A

Succinate Thiokinase

*generates GTP

11
Q

What enzyme produces FADH2 in the TCA cycle?

A

Succinate Dehydrogenase (aka. Complex II of ETC)

12
Q

When the cellular ATP levels are low, the activity of the TCA cycle is ___.

A

Increased

13
Q

___ reaction replenish intermediates of the TCA cycle.

Examples

A

Anaplerotic

  • FED: Pyruvate —> OAA
  • FASTING: Asn —> Asp —> OAA
  • FASTING: Gln / Pro / His / Arg —> Glu —> alpha-ketoglutarate
  • FASTING: Thr / Met / Ile / Val —> Propionyl CoA —> Succinyl CoA
  • FASTING: Phe / Tyr / Asp —> Fumarate
14
Q

___ inhibits Pyruvate Carboxylase from converting Pyruvate into OAA.

A

Insulin

15
Q

Oncometabolites of the TCA cycle include ___ and ___.

A

Citrate

2-hydroxyl glutarate

16
Q

OxPhos takes place in the ___.

A

Inner-mitochondrial membrane

17
Q

Goals of OxPhos:

A
  1. Transfer electrons (from NADH/FADH2 to oxygen)
  2. Establish a proton gradient
  3. Synthesize ATP
18
Q

Proton motive force is made by:

A
  1. pH gradient (Direction of H+ flow)

2. Membrane potential (“non-leakiness” of membrane)

19
Q

___ inhibits ATPase by disrupting the proton transport through the channel.

A

Oligomycin

20
Q

1 mol ATP requires passage of ____ H+.

A

3+1

21
Q

___ is the only ETC complex that does not pump protons across the innermembrane.

A

Complex II

22
Q

___ transfers electron to molecular oxygen.

A

Complex IV

23
Q

Inhibition of electron transfer down the ETC causes a ___ in the pumping of protons.

A

Decrease

24
Q

OxPhos is sensitive to ___ and ___.

A

Oxygen

[ATP/ADP] ratio

25
Q

____ disrupts the proton gradient and causes heat production instead of ATP synthesis.

A

Uncoupling (proton leak)

26
Q

DNP is an _____ that disrupts the proton gradient, thereby causing a ___ in ATP synthesis.

A

Uncoupling agent / decrease

27
Q

Shuttles are important because ____ cannot enter the mitochondria on its own.

A

NADH

28
Q

Malate-Aspartate Shuttle

Vs.

Glycerophosphate Shuttle

A

Malate-Aspartate Shuttle

  • occurs in heart / liver / kidney
  • NADH is shuttled into the mitochondrial matrix
  • NADH enters ETC at Complex I
  • reversible (depends on the fact that OAA cannot pass membranes)

Glycerophosphate Shuttle

  • occurs in muscle and brain
  • electrons from FADH2 are shuttled into CoQ
  • irreversible