Metabolism - Lecture Thirty Flashcards
Acetyl-CoA and The Citric Acid Cycle
Where does the Citric Acid Cycle (CAC) occur?
In the mitochondria
Citric Acid Cycle arranged into two parts
Release of carbon
Regeneration of the starting molecule
Key reaction in. the Citric Acid Cycle
Condensation of acetyl-CoA with oxaloacetate
Condensation of acetyl-CoA with oxaloacetate
Two carbon entering the Citric Acid Cycle as acetyl-CoA is attached to four carbon oxaloacetate to produce six carbon citrate
Where does the energy for the condensation of acetyl-CoA with oxaloacetate reaction come from?
Hydrolysis of CoA from acetyl-CoA
Isomerisation of citrate
Rearrangement of citrate to isocitrate makes the molecule susceptible to decarboxylation, both steps are catalysed by aconitase
Isomerisaiton of citrate: conversion of citrate to isocitrate
Makes the molecule susceptible to decarboxylation
Isomerisation of citrate: fluorocitrate
Binds to and inhibits aconitase (competitive, then inactivation)
Removal of the 1st carbon
An oxidative decarboxylation
Reaction occurs in two steps: oxidation then decarboxylation Energy captured in NADH
Removal of the 2nd carbon
A second oxidative decarboxylation
Very similar to the pyruvate dehydrogenase reaction Energy captured in NADH
Succinyl-CoA to succinate
The removal of the CoA releases enough energy to drive the synthesis of GTP (equivalent of ATP)
Substrate-level phosphorylation
The DIRECT use of energy from a substrate molecule to drive the synthesis of ATP
Succinate to oxaloacetate
The reactions used to convert succinate to oxaloacetate are very similar to β-oxidation
A shared reaction
The succinate dehydrogenase (SDH) reaction is shared between the CAC and the electron transport chain (ETC)
Succinate dehydrogenase location
Inner mitochondrial membrane and uses FAD
