Module 04 - Preparing for the TCA Cycle (Section 03) Flashcards
What is the substrate of rhe TCA cycle?
Acetyl-CoA
Once produced by glycolysis in the cytosol, where is pyruvate transported? How?
to the mitochondrial matrix by a specific transporter molecule
What does the PDH complex do?
catalyzes the oxidative decarboxylation (removal of CO2) of pyruvate, as well as the transfer of the acetyl group to coenzyme A
What is the first level of PDH complex regulation?
allosteric regulation of the enzyme itself
What does acetyl-CoA do to the PDH complex?
it inhibits the complex by increased acetly-CoA levels through product inhibition
What does pyruvate do to the PDH complex?
it activates the complex in a feedforward mechanism
What does NADH do to the PDH complex?
it inhibits the complex by increased levels of NADH, which can indicate that there is too much NADH for the ETC
What does ADP do for the PDH complex?
it is activated by increased levels of ADP, which indicates the cell is in an energy poor state
What does ATP do for the PDH complex?
it is inhibited by ATP, which indicates the cell is in an energy rich state
When is the PDH complex active?
when unphosphorylated; favoured by energy poor state
When is the PDH complex inactive?
when phosphorylated; favoured by energy rich state
What is the role of PDH Kinase?
- inactivates the PDH complex by phosphorylation
What is PDH Kinase’s activity allosterically increased by?
ATP, acetyl-CoA, NADH
What is PDH Kinase’s activity allosterically decreased by?
pyruvate, ADP, NAD+
What is the role of PDH Phosphatase?
- activates the PDH complex by desphosphorylating it
