TCA Cycle Flashcards
what are all fuels broken down into that is the source of the TCA cycle?
acetyl CoA
what provides the link between glycolysis and the TCA cycle?
the pyruvate dehydrogenase complex (PDH)
where is the PDH complex located in the cell?
the mitochondrial matrix
what is the main goal of the PDH complex?
to conver pyruvate to acetyl-CoA
what is the red subunit, E1, of PDH
pyruvate dehydrogenase
what is the yellow subunit, E2, of PDH?
transacetylase core
what is the green subunit, E3, of PDH?
dihydrolipoyl-dehydrogenase
what is the end product of the PDH complex?
1 mol of NADH/H+ per one mol of pyruvate
what is the overall reaction of the PDH complex (what kind of reaction)?
oxidation
what are the two other names for the TCA cycle?
Krebs Cycle and Citric Acid cycle
what does TCA stand for?
tricarboxylic acid cycle
how many reaction take place in the TCA cycle?
8
of all the reactions that take place in the TCA cycle how many are energy-providing?
5
does the TCA cycle require O2 directly?
no, but it is still considered aerobic because it takes place in the mitochondria
how many ATP “equivalents” of energy does the TCA cycle provide?
12
what are the “ATP equivalents” that the TCA cycle provides?
3NADH/H+, 1FAD, and 1GTP
where does the TCA get the oxygen needed for the oxidation of the CH3CO- portion?
from water
how many CO2 molecules are produced by the oxydation of the CH3CO- group?
2 CO2
what are defined as enzymes that remove 2H+ along with 2e- and transfer them to a cofactor?
dehydrogenases
another word to describe dehydrogenation in this instance is….?
oxidation
how many ATP can be taken from each NADH/H+
3 ATP
how many ATP can be taken from FADH2?
2 ATP
how many ATP can be made from 1 GTP?
1 ATP
what is the first enzyme of the TCA cycle?
citrate synthase
what does citrate synthase do?
combines Acetyl CoA and oxaloacetate to be citrate, gives of CoASH
what is the second enzyme of the TCA cycle?
aconitase
what does aconitase do?
it converts citrate to isocitrate by an isomerization reaction by dehydration the rehydration with the same H2O molecule
what is the first enzyme that provides energy in the TCA cycle? what is made?
isocitrate dehydrogenase, 1 mol of NADH/H+
what is the 3rd enzyme of the TCA cycle?
isocitrate dehydrogenase
isocitrate dehydrogenase couples what two reactions?
oxidation and decarboxylation
what is the 4th enzyme in the TCA cycle?
alpha-ketoglutarate dehydrogenase complex
what does the alpha-ketoglutarate dehydrogenase complex do?
converts alpha-ketoglutarate to succinyl CoA
what complex resembles the PDH complex?
alpha-ketoglutarate dehydrogenase complex
how many enzymes are involved in the alpha-ketoglutarate dehydrogenase complex?
5
what is generated by the alpha-ketoglutarate dehydrogenase complex?
1 mol of NADH/H+
what is the second enzyme the provides energy in the TCA cycle?
the alpha-ketoglutarate dehydrogenase complex
what two reactions are coupled by alpha-ketoglutarate dehydrogenase complex?
decarboxylation and acyl transfer to coenzyme A
what is TPP?
thiamine pyrophosphate
what does TPP do?
binds the aldehye generated from decarboxylation of alpha-keotglutarate
in terms of the TCA cycle what is TPP?
a coenzyme of the alpha-ketoglutarate dehydrogenase complex
in terms of the TCA cycle what is lipoic acid?
a coenzyme of the alpha-ketoglutarate dehydrogenase complex
what does lipoic acid do?
acts as transferring ‘crane arm’ between TPP and coenyzme A by transferring a succinyl-residue
what allows lipoic acid to act as a crane arm?
it’s reactive disulfide bond
which coenzyme of the alpha-ketoglutarate dehydrogenase complex generates energy, and in what form?
lipoic acid, 1NADH/H+
what does FAD stand for?
flavin-adenine-dinucleotide
what does FAD do?
regenerates lipoic acid
how many reactions does CoA participate in the celll?
about 100
what does coenzyme A do?
forms the final energy-rich thioester bond with the product of the reaction, to become succinyl-CoA
can lipoic acid be made by our cells?
yes, but it is also available as a supplement
