TCA Cycle: Citrate Synthase

Question 1

With what enzyme does the TCA Cycle begin?

Answer 1

Citrate synthase

Question 2

Which enzyme catalyzes the condensation of acetyl-CoA and oxaloacetate?

Answer 2

Citrate synthase

Question 3

Carbons from which types of molecules enter the TCA cycle at citrate synthase?

Answer 3

Carbs, fatty acids, and amino acids

Question 4

True or false: The condensation reaction of acetyl-CoA and oxaloacetate by citrate synthase is ordered sequential, and acetyl Co-A must bind before oxaloacetate.

Answer 4

False: The condensation reaction of acetyl-CoA and oxaloacetate by citrate synthase is ordered sequential, and oxaloacetate must bind before acetyl Co-A.

Question 5

Which molecule must citrate synthase bind first, oxaloaceate or acetyl-CoA?

Answer 5

oxaloacetate

Question 6

What is the structure of citrate synthase?

Answer 6

Dimer whose 2 domains form a cleft that contain the oxaloacetate binding site. When oxaloacetate binds, the enzyme’s smaller domain rotates 18 degrees, generating the acetyl-CoA binding site and excluding water.

Question 7

Is the reaction catalyzed by citrate synthase that forms citrate and CoA exergonic or endergonic?

Answer 7

Exergonic

Question 8

What are the products of the reaction catalyzed by citrate synthase?

Answer 8

citrate and CoA