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MEH > Carbs 3 > Flashcards

Carbs 3 Flashcards

1
Q

What must happen to pyruvate before it enters the TCA cycle

A

converted to acetyl CoA

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2
Q

What enzyme is require to convert pyruvate to acetyl CoA

A

pyruvate dehydrogenase

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3
Q

Is the reaction from pyruvate to acetyl Co A reversible

A

no

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4
Q

What is a byproduct of converting pyruvate to acetly CoA

A

CO2

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5
Q

How is pyruvate dehydrogenase regulated

A
  • acetyl CoA allosterically inhibits
  • ATP, NADH inhibit
  • ADP activates
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6
Q

Where does the TCA cycle occur

A

mitochondria

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7
Q

What is the importance of the TCA cycle

A
  • generates reducing power
  • useful intermediates
  • all C-C and C-H bonds broken
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8
Q

What is required for the TCA cycle to occur

A

oxygen
oxaloacetate

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9
Q

What combines with acetyl CoA to form citrate

A

oxaloacetate C4

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10
Q

What enzyme converts the intermediate isocitrate to a-ketoglutarate

A

isocitrate dehydrogenase

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11
Q

What is the rate limiting enzyme in the TCA cycle

A

isocitrate dehydrogenase

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12
Q

what is the second necessary enzyme in the TCA cycle

A

a-ketoglutarate dehydrogenase

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13
Q

What are the products of the TCA cycle

A
  • 6 NADH
  • 2 FADH2
  • 2 GTP
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14
Q

What are the uses of the intermediates

A

citrate- fatty acids
a-ketoglutarate- amino acids
succinate- amino acids, haem
malate- amino acids
oxaloacetate- amino acids, glucose

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15
Q

How is oxaloacetate replenished

A

pyruvate + CO2 + ATP + H2O –> oxaloacetate + ADP + Pi + 2H+
enzyme: pyruvate carboxylase

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16
Q

How are intermediates in the TCA cycle replaces

A

breakdown of amino acids

17
Q

How is the TCA cycle regulated

A

ATP/ADP ratio
NADH/NADP ratio
isocitrate dehydrogenase allosterically regulated

18
Q

Where does stage 4 of metabolism occur

A

inner mitochondrial membrane

19
Q

What do NADH and FADH2 contain

A

high energy electrons

20
Q

How does the ETC work

A
  • electrons from NADH and FADH2 transferred through a series of carrier molecules called proton translocating complexes to oxygen
  • so NADH and FADH2 become oxidised to NAD and FAD and PTC become reduced
21
Q

What do the PTCs do with the free energy transferred to them by NADH and FADH2

A

move protons from matrix to intermembrane space as inner membrane itself is impermeable to protons

22
Q

What does the movement of protons across inner membrane create

A

proton motive force and electrochemical gradient

23
Q

what is the proton motive force used for

A

as protons can only move back through ATP synthase gives the energy for ATP synthesis

24
Q

What is oxygen used for

A

terminal electron acceptor

25
Q

What are the ETC and oxidative phosphorylation said to be

A

tightly coupled

26
Q

what is the net yield of ATP from glycolysis

A
  • 2 ATP
  • 2 NADH= 5 ATP
27
Q

What is the yield of ATP from formation of acetly CoA

A

2 NADH= 5ATP

28
Q

What is the yield of ATP from the TCA cycle

A

2 GTP= 2ATP
6 NADH = 15 ATP
2 FADH2 = 3 ATP

29
Q

What is the overall net yield of ATP

A

32 ATP per glucose

30
Q

What are some inhibitors of ETC

A

anaerobic conditions
CO
CN (cassava)

31
Q

How do inhibitors stop ETC

A

they bind to the haem group in PTC3 so oxygen not bound so cannot act as terminal electron acceptor so electron transport

32
Q

How do uncouplers stop oxidative phosphorylation

A

uncouplers increase permeability of inner membrane to protons so dissipate proton motive force as heat

33
Q

What are some examples of uncouplers

A

dinitrophenol
dinitrocresol

34
Q

Where is brown adipose tissue found

A

newborns
hibernating animals

35
Q

Why is brown adipose tissue useful for infants

A

contains natural uncoupling proteins to generate heat as they cannot shiver
UCP1 most important as it contains thermogenin

36
Q

What is the difference in ox and substrate phosphorylation in terms of enzymes

A

ox: require mitochondrial membrane-bound complexes
sub: soluble membranes

37
Q

What is the difference in ox and substrate phosphorylation in terms of
directness

A

ox: indirect as energy from proton gradient
sub: direct, energy from hydrolysis of high energy bond

38
Q

What is the difference in ox and substrate phosphorylation in terms of oxygen

A

ox: requires O2
sub: can occur without

39
Q
A

MEH (12 decks)

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