Sean - TCA Cycle Regulation Flashcards
Where is the TCA Cycle regulated?
Reaction 1
Reaction 3
Reaction 4
What is reaction 1
(2)
The formation of citrate from acetyl CoA and oxaloacetate
Catalysed by citrate synthase
What is reaction 3
The oxidation of isocitrate to alpha-ketoglutarate and Carbon dioxide gas
What is reaction 4
The oxidation of alpha-ketoglutarate to succinyl-CoA and carbon dioxide gas
What is reaction 1 called?
Citrate synthesis
What is the catalyst in reaction 1?
Citrate synthase
What activated reaction 1?
ADP
What inhibits reaction 1?
NADH
Succinyl-CoA
Citrate
ATP
Why does high ADP activate reaction 1?
High ADP is associated with low energy reserves
Why does high ATP and NADH inhibit reaction 1?
These are associated with sufficient energy reserves -> no need for TCA cycle
What does citrate and succinyl CoA do in reaction 2?
(2)
These are indicators of the rate of flow through the citric acid cycle
When elevated they inhibit citrate synthase to prevent more acetyl CoA entering the pathway
What activates reaction 3?
Ca2+
ADP
What inhibits reaction 3?
ATP
What is special about reaction 3?
It senses the energy reserves in the cell before continuing
How does Ca2+ activate isocitrate dehydrogenase (reaction 3)?
(2)
Increased intracellular Ca2+ indicates that the cell is active and will soon move, grow or divide
All of these cellular functions require a lot of energy
