Human Biochemistry: Citric Acid Cycle

All enzymes and steps of the Citric Acid Cycle from Ch. 16

What is the overall process of the Citric Acid Cycle?

Oxidizing the acetyl group of Acetyl CoA into 2 CO2 while producing NADH, FADH2 and ATP

(Step 1) What are the 1) Substrates and 2) Products of the enzyme Citrate synthase? 3) Is this reversible?

1) Acetyl CoA and oxaloacetate 2) citrate and CoA 3) No

What is important about Citrate that is produced in Step 1 of the CAC?

Citrate is the precursor for fatty acid synthesis

(Step 2) What are the 1) Substrates and 2) Products of the enzyme Aconitase?

1) citrate 2) isocitrate

(Step 3) What are the 1) Substrates and 2) Products of the enzyme Isocitrate dehydrogenase?

1) Isocitrate and NAD+ 2) alpha-ketoglutarate and NADH and H+ and CO2

(Step 4) What are the 1) Substrates and 2) Products of the Alpha-ketoglutarate dehydrogenase complex?

1) alpha-ketoglutarate, CoA, and NAD+ 2) succinylcholine CoA, NADH, H+, and CO2

(Step 5) What are the 1) Substrates and 2) Products of the enzyme of Succinate thiokinase?

1) succinyl CoA, ADP, and Pi 2) succinate, CoA, and ATP

(Step 6) What are the 1) Substrates and 2) Products of the enzyme of Succinate dehydrogenase?

1) succinate and FAD 2) fumarate andFADH2

(Step 7) What are the 1) Substrates and 2) Products of the enzyme of Fumarase?

1) Fumarate and H2O 2) malate

(Step 8) What are the 1) Substrates and 2) Products of the enzyme of Malate dehydrogenase?

1) malate and NAD+ 2) oxaloaxetate, NADH, and H+

What is special about oxaloacetate in the Citric Acid Cycle?

It is reformed to restart the cycle

What is the overall equation for the Citric Acid Cycle for 1 molecule of acetyl CoA?

acetyl CoA + ADP + Pi + 3 NAD+ + FAD + H2O → 2 CO2 + 3 NADH + 3H+ + FADH2 + ATP + CoA

How much mitochondrial NADH and FADH2 is made in total in the citric acid cycle per 1 molecules of glucose? How many ATP?

6 NADH and 2 FADH2 and 2 ATP

Does the Citric Acid Cycle create any cytosolic NADH or FADH2?

No

What are some processes that the Citric Acid cycle plays a major role in? (5)

Gluconeogenesis, Transamination, Deamination, Urea cycle, Fatty acid synthesis and oxidation