The Citric Acid Cycle

What is the TCA for?

Produces energy from glucose products

Net reaction of TCA?

2 Acetyl-CoA + 6 NAD+ + 2 FAD + 2 ADP → 4CO2 + 6 NADH + 2 FADH2 + 2 ATP + 6 H+

Where does the TCA occur?

Mitochondrial matrix

What are the 3 committing steps of TCA? Name the enzymes.

Citrate Synthase, Isocitrate dehydrogenase, and a-keotglutarate dehydrogenase

What regulates citrate synthase?

Positive: Energy charge, need for TCA products

Negative: ATP, NADH, Citrate, Succinyl-CoA

What regulates Isocitrate Dehydrogenase?

Positive: Energy Charge, need for TCA Products

Negative: ATP, NADH

What regulates a-ketoglutarate dehydrogenase?

Positive: Need for TCA products

Negative: NADH, Succinyl-CoA

What is the chemical logic of the TCA?

Citric acid intermediates are more easily oxidized than acetate (product of pyruvate) and therefore makes e- transfer more efficient

What is the pattern for Carbon tracing from Glucose?

Carbon 3/4: 100% Lost before TCA

Carbon 2/5: 100% Lost in round 2 in TCA as CO2

Carbon 1/6: 50% Lost in round 3, 25% in round 4, …

What in an anaplerotic reaction?

A reaction that replenishes TCA intermediates

Why is the TCA amphibolic?

Does both anaplerosis and cataplerosis to use and regenerate intermediates - cyclical

How is Oxaloacetate replenished?

PEP Carboxylase and Pyruvate Carboxylase

What other process is Pyruvate carboxylase used in?

Gluconeogenesis

What activates pyruvate carboxylase?

Acetyl-CoA

What cofactor does pyruvate carboxylase use?

Biotin