Citric Acid cycle Flashcards
what is the citric acid cycle?
gateway to aerobic metabolism for any molecule that can be transformed into an acetyl group or dicarboxylic acid
the citric acid cycle is an important source of precursors?
storage form of fuels
building blocks of amino acids
building blocks of nucleotide bases
cholesterol, heme (porins)
what is the structure of mitochondria?
compartmentalisation by membranes
create gradients that drive ATP synthesis
matrix
inner mitochondrial membrane
outer mitochondrial membrane
what’s the equation of formation of acetyl coA?
pyruvate + coA + NAD+ —> acetyl coA + CO2 + NADH
complex of enzymes that catalyse this reaction
key points of formation of acetyl co A
pyruvate transported into mitochondria
- specific carrier
pyruvate oxidatively decarboxylated to acetyl co A by pyruvate dehydrogenase
what is pyruvate dehydrogenase?
giant complex
involved in the multi step reaction
all three steps happen because of pyruvate dehydrogenase component
oxaloacetate +acetyl coA —> cityl coA —> citrate
catalysed by citrate synthase
reaction is an aldol condensation followed b hydrolysis
citric coA is an intermediate
remove coA in hydrolysis reaction
citrate —> cis-Aconitate —> isocitrate
catalysed by aconitase
cis-aconitate is an intermediate
iron facilitates the dehydration/hydration reactions
REMEMBER THIS
isocitrate —> oxalosuccinate —> a-ketogluterate
NAD+ -> NADH + H+ H+->CO2
isocitrate dehydrogenase
a-ketogluterate + NAD+ + CoA —> succinylcholine coA + CO2 + NADH
a-ketogluterate dehydrogenase complex
key step in production of NADH
takes out 2e-
removal of 4e- in total
NADH is liberated
succinylcholine CoA + Pi + GDP —> succinate + CoA + GTP
succinylcholine coA synthetase
creates GTP from GDP
succinate —> fumigate —> malate —> oxaloacetate
succinate -> fumerate
succinate dehydrogenase
fumerate -> malate
fumerase
malate ->oxaloacetate
malate dehydrogenase
regulated by concentrations of ATP and NADH
where are the control points in the citric acid cycle?
pyruvate dehydrogenase
- irreversible reaction
isocitrate dehydrogenase
- inhibited by ATP and NADH
a-ketogluterate dehydrogenase
- inhibited by ATP, succinyl coA and NADH
what is the overall equation of the citric acid cycle?
acetyl coA + 3NAD+ + FAD + GDP + Pi
|
2co2 + 3NADH + FADH2 + GTP + CoA
overall product yields
2 x CO2
1 x GTP
3 x NADH
1 x FADH2
