AP Biology : Understand pyruvate decarboxylation

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understand Pyruvate Decarboxylation

During pyruvate decarboxylation reaction, pyruvate is converted to _______________ compound, through a reaction called ______________ .

Possible Answers:

acetyl CoA; oxidative decarboxylation

acetyl CoA; reductive decarboxylation

ATP; decomposition

NADH; oxidative decarboxylation

Correct answer:

acetyl CoA; oxidative decarboxylation

Explanation:

Pyruvate decarboxylation is an oxidative decarboxylation reaction, or an oxidation reaction where a carboxylate group is removed. This reaction converts pyruvate which was produced through glycolysis to acetyl CoA to be used in the Citric Acid Cycle.

Example Question #2 : Understand Pyruvate Decarboxylation

Which enzyme complex catalyzes the pyruvate decarboxylation reaction?

Possible Answers:

pyruvate dehydrogenase complex

pyruvate oxidase

pyruvate reductase

acetyl dehydrogenase

Correct answer:

pyruvate dehydrogenase complex

Explanation:

The pyruvate dehydrogenase complex is an enzyme complex that consists of 3 enzymes, which work together to catalyze the pyruvate decarboxylation reaction, where pyruvate is converted to acetyl CoA.

Example Question #1 : Understand Pyruvate Decarboxylation

Where does the pyruvate decarboxylation reaction occur?

Possible Answers:

Cristae

Mitochondrial matrix

Outer mitochondrial membrane

Cytosol

Correct answer:

Mitochondrial matrix

Explanation:

Pyruvate decarboxylation occurs in the mitochondrial matrix. The acetyl CoA produced from the pyruvate decarboxylation reaction will undergo the Citric Acid cycle also in the mitochondrial matrix.

Example Question #2 : Understand Pyruvate Decarboxylation

For each glucose molecule that undergoes glycolysis, how many acetyl CoA molecules are produced at the end of pyruvate decarboxylation?

Possible Answers:

1

32

2

4

Correct answer:

2

Explanation:

During glycolysis, for each molecule of glucose, two molecules of pyruvate are produced ( glucose+ NAD+ + 2 ADP + 2Pi-> 2 pyruvate+ 2 ATP + 2NADH+. These 2 molecules of pyruvate then undergo the pyruvate decarboxylation reaction: 2(pyruvate+ CoA-SH+ NAD+ -> NADH+ CO2+ acetyl CoA).

Example Question #5 : Understand Pyruvate Decarboxylation

During the pyruvate decarboxylation reaction, acetyl CoA is produced through which type of bond linking an acetyl group to coenzyme A?

Possible Answers:

hydrogen bond

thioester bond

acetylase bond

ionic bond

Correct answer:

thioester bond

Explanation:

During the pyruvate decarboxylation reaction , a thioester bond links the acetyl group of pyruvate with coenzyme A to produce acetyl CoA.

Example Question #3 : Understand Pyruvate Decarboxylation

Which is not a product of pyruvate decarboxylation reaction?

Possible Answers:

acetyl 

Correct answer:

Explanation:

The pyruvate decarboxylation reaction is pyruvate+ CoA-SH+ NAD+ -> NADH+ CO2+ acetyl CoA.

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