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biochem > citric acid cycle > Flashcards

citric acid cycle Flashcards

1
Q

stage one of citric acid cycle is

A

acetyl coA production

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2
Q

pyruvate undergoes ____ ___ to produce acetyl co a

A

oxidative decarboxylation

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3
Q

the citric acid cycle occurs in

A

mitochondrial matrix

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4
Q

within step one of aerobic respiration (citric acid cycle) there are ___ seperate enzymatic activities and _ cofactors

A

3, 5

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5
Q

what are the five cofactors

A

TPP, NAD, lipoate, FAD, Coa-SH

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6
Q

catabolic

A

breaking down

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7
Q

NAD is an electron carrier and carries __ electrons

A

2

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8
Q

TPP does what two actions

A

C-C bond cleavage and two carbon transfer

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9
Q

there are three major steps of respiration what are they

A
  1. acteyl co a production
  2. acetyl co a oxidation
  3. electron transfer and oxidative phosphorylation
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10
Q

respiration is all about pushing ___

A

electrons

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11
Q

with acetyl coa procution by pyruvate there is what relwased

A

co2

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12
Q

the enzyme complex used to convert pyruvate to acetyl coa is

A

pyruvate dehydrogenase complex (has three subunits)

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13
Q

pyruvate dehydrogenase complex has ____ ____ in which intermediated never leave the complex

A

substrate channeling

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13
Q

lipoate is convently bound to a ____ on E2; the result is

A

lysine; lipoamide

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14
Q

FAD is an ___ ____

A

electron acceptor

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15
Q

E2 has two domains, lysine to which the lipoate is attached is in one but the the other is an ____

A

active site

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16
Q

lipoate can exist in three states

A
  1. oxidized
  2. reduced
  3. acetylated
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17
Q

lipoate can carry ___ and ____

A

electrons and acetyl co a

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18
Q

FAD cannot ____ it is present and attached to E3 subunit

A

leave (NAD can move in and out )

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19
Q

coezyme A carries ____ groups; has a reactive thiol group

A

acetyl

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20
Q

TPP has an _____ _____ which readily leaves

A

acidic proton

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21
Q

once the proton leaves the E1 TPP will readily attack the incoming carbonyl carbon of ___; which releases CO2

A

pyruvate

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22
Q

the remaing part of the pyruvate on TPP gets converted to _____

A

hydroxyethyl TPP

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23
Q

The E2 lipoamide has a lysine amino acid linker which will swing into E1 and coverted that group in E1 to what

A

acytelated lipoamide

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24
Q

next in E2 subunit CoA will diffuse in and pick up acetyl group to become

A

acetyl CoA

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25
Q

the reduced lipoamide drops off electrons to FAD (E3) making it

A

FADH2

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26
Q

NAD will pick up electrons from FADH2 and becomes

A

NADH2

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27
Q

Once pyruvate is converted to Acetyl CoA it is irreversible but Acetyl CoA can either go to ___ __ __ or _ _ _

A

citric acid cycle or fatty acid synthesis

28
Q

high levels of ATP would cause Acetyl CoA to choose

A

fatty acid synthesis

29
Q

The PDH complex is alosterically regulated by __ ____ and ___

A

AMP, CoA and NAD+

30
Q

The PDH complex is ___ by dephosphorylation of E1

A

activated

31
Q

stage 2 of the citric acid cycle uses 2C (acetyl coa) which enters and combines with ____

A

4C oxaloacetate

32
Q

used in both anabolic and catabolic processes; intemediates leave/join at different points

A

amphibolic (citric acid cycle does this)

33
Q

the 6C molecule formed from acetyl coA and oxaloacetate is

A

citrate

34
Q

step one is a condensations step where acetyl coA and oxaloacetate are are combined. What enzyme is used? which gives you?

A

citrate synthase; citrate

35
Q

step 2 is generating a better substrate for step 3; which ___ to ____

A

citrate to isocitrate

36
Q

citrate is a ____ alcohol which makes it a poor substrate for oxidation

A

tertiary

37
Q

the intermediate between citrate and isocitrate is

A

cis-aconitate

38
Q

____ is the enzyme which helps use water to change citrate to isocitrate

A

aconitase

39
Q

_____ of the citrate leads to cis C double bond C

A

dehydration

40
Q

step 3 is the first oxidation in which isocitrate becomes oxidized by ____

A

NAD

41
Q

step 3 is catalyzed by ____ ____ and requires manganese ion to stabilize

A

isocitrate dehydrogenase

42
Q

isocitrate is converted to ____ by NAD (oxidation) then to ____ with release of (decoarboxylation)

A

oxalosuccinate; alpha ketoglutarate

43
Q

step 4 is the second oxidation where alpha ketoglutarate gets converted to ____ ____ (oxidative decarboxylation)

A

succinyl-CoA

44
Q

step 3 ends in succinyl-CoA which results in high group transfer potential with ___

A

thioester

45
Q

step 5 is a substrate level phosphorylation where succinyl coA becomes _____

A

succinate

46
Q

step 5 generates ____

A

GTP

47
Q

catalyzes condensation reactions using energy of NTPs

A

synthetase

48
Q

what enzyme converts succinyl coA into succinate (enzyme is not named correctly; typically there will be a breakage or cleavage yet that does not happen)

A

succinyl-CoA synthetase

49
Q

step 5 also produces a ____

A

GTP

50
Q

all triphosphates are essentially ____ and interconvertible in terms of energy

A

equal

51
Q

step 6 is the third oxidation in which succinate is converted to ____

A

fumarate

52
Q

what enzyme is used for step 6

A

succinate dehydrogenase

53
Q

step 6 is the only reaction in which ____ is the electron acceptor

A

FAD

54
Q

succinate dehydrogenase is the only enzyme not in the ___; it is bound to inner mitochondrial matrix

A

matrix

55
Q

step 7 is hydration where fumarate becomes ____ (uses fumarase as enzyme)

A

malate

56
Q

within step 7 addition of water occurs in two steps what are they

A
  1. hydroxylation generates a carbanion
  2. protonation neutralizes the carbanion
57
Q

fumarase only adds water in ___ across the double bond

A

trans

58
Q

step 8 is an oxidation where you go from L-malate to (high G- unfavorable; product removal pushes it forward!)

A

oxaloacetate

59
Q

in step 8 ___ is the electron acceptor and the enzyme is

A

NAD, and malate dehydrogenase

60
Q

one ___ is produced per cycle

A

GTP

61
Q

electrons from cirtic acid cycle REDUCE NAD+ and FAD; which are then used to make ATP there are ___ ATP per FADH2 and ___ ATP per NADH

A

1.5, 2.5

62
Q

every 4 protons gives you one ATP and NADH pushed ten protons so ___ ATP per NADH

A

2.5

63
Q

alpha ketoglutarate can leave pathway and make ___

A

purines

64
Q

pyruvate can make oxaloacetate to make aspartate which makes

A

amino acids, purines and pyrimidines

65
Q

the ____ reaction is when pyruvate will bind to bicarboinate in presence of ATP and ezyme is ___ will give you oxaloacetate to run citric acid cycle (you have to have it!!)

A

analplerotic; pyruvate carboxylase

66
Q

the anaplerotic reaction will replenish ___ for the cycle

A

metabolites

67
Q

pyruvate carboxylase wont function unless acetyl coA is abundant, why?

A

acetyl coA will build up and will activate oxaloacetate which can then make citrate

68
Q

high acetyl coA negatively regulated PDH; why?

A

high acetyl CoA shows a fed state so don’t need to run citric acid cycle

biochem (17 decks)

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