The Catabolism of Pyruvate Flashcards
What is the NET yield of glycolysis?
2ATP 2NADH
How is NAD+ regenerated?
By oxidative metabolism of pyruvate - this will allow continuation of glycolysis
Where does the TCA cycle take place?
In the matrix of the mitochondria
What does the inner membrane of the mitochondria contain?
Proteins for electron transport chain, ATP synthase and transport proteins
How does pyruvate enter the mitochondrial matrix?
H+ gradient from cytosol to matrix
Pyruvate transporter: H+/pyruvate symport by facilitated diffusion
A similar process regulated ADP, ATP and inorganic phosphate (Pi) movement into and out of mitochondria
How is pyruvate metabolised to Acetyl-CoA?
The pyruvate dehydrogenase complex (PDC) catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA
PDC consists of 3 enzymes and is allosterically regulated
by phosphorylation
PDC activity determines glucose oxidation in well oxygenated tissues.
The reaction is irreversible. Acetyl-CoA cannot be converted back to pyruvate.
What are the 3 enzymes of PDC?
Pyruvate dehydrogenase
Dihydrolipoyl transacetylase
Dihydrolipoyl dehydrogenase
All enzymes of the TCA cycle are located in the mitochondrial matrix apart from which one?
Succinate dehydrogenase - integrated within the inner mitochondrial membrane
What does each turn of the TCA cycle involve?
The uptake of two carbon atoms in the form of acetyl-CoA and the release of 2 carbon atoms as CO2.
What does the one substrate level phosphorylation reaction result in?
The formation of GTP from GDP and Pi - potential energy
Describe the control of the TCA cycle?
High ATP, NADH and acetyl-CoA means plenty of energy
High ADP and NAD+ means lack of energy
High succinyl-CoA and acetyl-CoA means plenty of precursor molecules for biosynthetic reactions
What is the NET yield for each molecule of glucose?
4 ATP 10 NADH 10 H+ 2 FADH+ 6 CO2
