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TCA cycle Flashcards

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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

Study These Flashcards
A

anabolic and catabolic

tca cycle

24
Q

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

Study These Flashcards
A

6co2

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

25
why is decarboxylation reaction easier for beta ketoacids?
resonance stabilized
26
which is unstable after decarboxylation: alpha or beta ketoacids?
alpha ketoacid (pyruvate) ---unstable carbanion, no resonance, no e sharing
27
net reaction for pdc
2 pyruvate +2NAD+ + 2CoASH --> 2 acetyl coA + 2 NADH +2CO2
28
what fixes the problem of pyruvate as an alpha ketoacid?
pyruvate dehudrogenase complex | it catalyzes the oxidation ofpyruvate to acetyl coA using thiamine pyrophsphate (TPP)
29
beri beri | wet v dry
thiamine deficiency wet --> cv system dry --> nervous system
30
who is at risk for thiamine defficiency?
alcoholics and those with low nutritional intake
31
reactive center in TPP?
thiazole ring
32
``` polyneuropathy parasthesia paresis(partial paralysis/weakness) psychiatric edema ```
thiamine deficiency symptoms
33
three enzymes of pdc
e1 - pyruvate decarboxylase e2 - transacetylase e3 - dihydolipoyl dehydrogenase
34
cofactors of e1 - pyruvate decarboxylase
TPP
35
cofactors of e2 - transacetylase
lipoic acid and coenzyme a
36
cofactors of e3 - dihydrolipoyl dehydrogenase
FAD and NAD+
37
three steps of TPP decarbxylation of pyruvate?
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
pdc reaction is...
-8 kcal.mol --> irreversible and favorable
39
pdc is regulated by..
phosphorylation and dephosphorylation at a serine residue - -dephosphorylated pdc is ACTIVE - kinase adds P, inactivating complex - Ca2+activates phosphatase --> turns PDC on
40
neurodegenerative disorder pediatric onset, weakness, hypotonia, ataxia, spasticity, dyspnea, opthalmoplegia, optic atrophy maternal, xlinked, auto recessive (all lethal)
leigh syndrome
41
how many atp is an NADH, gtp, and FADH2 worth?
``` nadh = 2.5 atp fadh2 = 1.5 atp gtp = 1 atp ```
42
coenzyme a in the pdc
part of transacetylase rxn | accepts acetyl group from acetyl lipoamide
43
between alpha ketoglutarate and malate, how many net ATP can be generated?
5
44
glucose to lactate versus complete oxidation atp production?
lactate conversion gives us 2 atp and complete oxidation gives 30-32...15x as great
45
three ways pdc can be activated
- ca2+ activates phosphotase - inhibition of a kinase by pyruvate - decrease NADH/NAD+ ratio
46
why does tca only run under aerobic conditions?
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
anaplerotic reactions...
are necessary because the biosynthesis of some aa require tca intermediates as precursors AND can convert pyruvate to oxaloacetate in mmmals
48
what requires biotin as a cofactor?
pyruvate carboxylase
49
glut =
5C
50
what keeps the tca cycle turning?
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
for every acetyl coa, how many oxaloacetates are made?
none! | used in next round of cycle
52
if citrate builds up, what enzyme is inhibited?
citrate synthase
53
what aa precursor can make more oxaloacetate?
aspartate
54
what aa can feed right into alpha ketoglutarate?
glutamate
55
succinyl coa can be replaced w ...
3c propionyl coA from fatty acids
56
when and where is fat synthesized?
in cytoplasm when citrate builds up due to excess acetyl coA

MSK (nlg) (10 decks)

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