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MSK (nlg) > TCA cycle > Flashcards

TCA cycle Flashcards

1
Q

which stage of glucose oxidation occurs in the cytoplasm of the cell?

A

glycolysis

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2
Q

how many co2 are produced in ten turns of tca?

A

2x10=20

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3
Q

which stage of respiration produces the most ATP directly when glucose is completely oxidized to carbon dioxide and water?

A

ETC and chemiosmosis

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4
Q

The oxygen consumed during cellular respiration is directly involved in…

A

accepting e in ETC

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5
Q

When hydrogen ions (H+) are pumped across the inner mitochondrial membrane, they form a proton gradient. ATP is then formed by a process called…

A

oxidative phosphorylation

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6
Q

In aerobic respiration, the electrons associated with the hydrogen atoms in glucose are transferred to…

A

oxygen through many steps

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7
Q

NADH + H+ is oxidized during which stage(s) of aerobic respiration in the cell?

A

ETC

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8
Q

making the entire inner mitochondrial membrane permeable to H+ would stop ?

A

atp synthesis

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9
Q

Where is the electron transport chain for cellular respiration located in a plant cell?

A

inner membrane of mitochondria

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10
Q 
all of the following are produced in glycolysis except...
                ATP
		pyruvate
		carbon dioxide
		NADH + H+
		heat
A

co2

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11
Q

TCA cycle occurs in…

A

mitochondrial matrix

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12
Q

in prokaryotes, tca occurs in

A

cytosol (proton gradient across PM)

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13
Q

how many enzymes does cycle use?

names?

A

8

  • citrate synthase
  • aconitase
  • isocitrate dehydrogenase
  • alpha ketoglutarate dehydrogenase
  • succinyl coA synthetase
  • succinate dehudrogenase
  • fumarase
  • malate dehydrogenase
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14
Q

from beginning to end, what is oxidized to what?

A

acetyl coa –>2 co2

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15
Q

Net products of tca

A 
two turns (2 acetylcoA) give:
2GTP
6NADH
2FADH2
2CO2
(one turn of cycle is half of that)
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16
Q

primary source of acetyl coa for tca?

A

glycolysis , sugar breakdown

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17
Q

what converts pyruvate from glycolysis to acetyl coa?

A

pyruvate dehydrogenase complex

decarboxylation

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18
Q

oxidation of fatty acids produces what?

A

acetyl coa

-alternate source for TCA cycle

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19
Q

in one turn of tca, how many carboxyl groups are lost as co2? which steps?

A

2

step 3 and 4

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20
Q

carbons lost as co2 come from?

A

oxaloacetate, NOT acetyl coA

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21
Q

acetyl coA carbons become…

A

oxaloacetate of next turn

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22
Q

in tca, what is the final e acceptor in the rxn catalyzed by succinate dehydrogenase?

A

FADH2

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23
Q

amphibolic

A

anabolic and catabolic

tca cycle

24
Q

in complete oxidation of glucose, how many atp andco2 made?

A

6co2

30 atp + 2 from gtp = 32 atp under max conditions

25
Q

why is decarboxylation reaction easier for beta ketoacids?

A

resonance stabilized

26
Q

which is unstable after decarboxylation: alpha or beta ketoacids?

A

alpha ketoacid
(pyruvate)

—unstable carbanion, no resonance, no e sharing

27
Q

net reaction for pdc

A

2 pyruvate +2NAD+ + 2CoASH –> 2 acetyl coA + 2 NADH +2CO2

28
Q

what fixes the problem of pyruvate as an alpha ketoacid?

A

pyruvate dehudrogenase complex

it catalyzes the oxidation ofpyruvate to acetyl coA using thiamine pyrophsphate (TPP)

29
Q

beri beri

wet v dry

A

thiamine deficiency
wet –> cv system
dry –> nervous system

30
Q

who is at risk for thiamine defficiency?

A

alcoholics and those with low nutritional intake

31
Q

reactive center in TPP?

A

thiazole ring

32
Q 
polyneuropathy
parasthesia
paresis(partial paralysis/weakness)
psychiatric
edema
A

thiamine deficiency symptoms

33
Q

three enzymes of pdc

A

e1 - pyruvate decarboxylase
e2 - transacetylase
e3 - dihydolipoyl dehydrogenase

34
Q

cofactors of e1 - pyruvate decarboxylase

A

TPP

35
Q

cofactors of e2 - transacetylase

A

lipoic acid and coenzyme a

36
Q

cofactors of e3 - dihydrolipoyl dehydrogenase

A

FAD and NAD+

37
Q

three steps of TPP decarbxylation of pyruvate?

A
  1. proton abstracted from thiamine by base creating tpp carbanion
  2. carbanion attacks carbonyl of pyruvate forming covalent intermediate
  3. co2 removed creating a beta ketoacid
38
Q

pdc reaction is…

A

-8 kcal.mol –> irreversible and favorable

39
Q

pdc is regulated by..

A

phosphorylation and dephosphorylation at a serine residue

  • -dephosphorylated pdc is ACTIVE
  • kinase adds P, inactivating complex
  • Ca2+activates phosphatase –> turns PDC on
40
Q

neurodegenerative disorder
pediatric onset, weakness, hypotonia, ataxia, spasticity, dyspnea, opthalmoplegia, optic atrophy
maternal, xlinked, auto recessive (all lethal)

A

leigh syndrome

41
Q

how many atp is an NADH, gtp, and FADH2 worth?

A 
nadh = 2.5 atp
fadh2 = 1.5 atp
gtp = 1 atp
42
Q

coenzyme a in the pdc

A

part of transacetylase rxn

accepts acetyl group from acetyl lipoamide

43
Q

between alpha ketoglutarate and malate, how many net ATP can be generated?

A

5

44
Q

glucose to lactate versus complete oxidation atp production?

A

lactate conversion gives us 2 atp and complete oxidation gives 30-32…15x as great

45
Q

three ways pdc can be activated

A
  • ca2+ activates phosphotase
  • inhibition of a kinase by pyruvate
  • decrease NADH/NAD+ ratio
46
Q

why does tca only run under aerobic conditions?

A

oxidized cofactors NAD and FAD are required for the oxidation reactions so aerobic conditions are needed to allow nadh and fadh2 to transfer their e into the ETC and regenerate nad and fad

47
Q

anaplerotic reactions…

A

are necessary because the biosynthesis of some aa require tca intermediates as precursors AND
can convert pyruvate to oxaloacetate in mmmals

48
Q

what requires biotin as a cofactor?

A

pyruvate carboxylase

49
Q

glut =

A

5C

50
Q

what keeps the tca cycle turning?

A

free energy of reactions, mainly -G (step 1 is -7.7, 3 is -5.3, and 4 is -8) so uphill last reaction to oxaloacetate is offset, and relative amount of NAD available

51
Q

for every acetyl coa, how many oxaloacetates are made?

A

none!

used in next round of cycle

52
Q

if citrate builds up, what enzyme is inhibited?

A

citrate synthase

53
Q

what aa precursor can make more oxaloacetate?

A

aspartate

54
Q

what aa can feed right into alpha ketoglutarate?

A

glutamate

55
Q

succinyl coa can be replaced w …

A

3c propionyl coA from fatty acids

56
Q

when and where is fat synthesized?

A

in cytoplasm when citrate builds up due to excess acetyl coA

MSK (nlg) (10 decks)

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