Which step(s) of the citric acid cycle involve oxidation of the substrate molecule?

Steps 3, 4, 6, and 8 of the citric acid cycle involve the oxidation of the substrate. This is indicated by the involvement of the redox cofactors NAD and FAD.

Which step(s) of the citric acid cycle involve a transfer of phosphate ion?

Step 5 involves the transfer of a phosphate ion. This is indicated by the involvement of inorganic phosphate (P ) or the involvement of GDP and GTP.

Which step(s) of the citric acid cycle involve a dehydration reaction (as part or all of the step)?

Only step 2 involves a dehydration. This is indicated by the water coming out of the cycle as the first reaction in the step. Step 2 consists of two reactions: an elimination (dehydration) followed by the addition of water in the opposite orientation.

Which step(s) of the citric acid cycle involve the formation of a thioester?

A thioester is formed in step 4 of the citric acid cycle. Coenzyme A is a thiol that condenses with one of the carboxyl groups on alpha

-ketoclutarate. [Succinyl-SCoA is a thioester.]

Which step(s) of the citric acid cycle involve a decarboxylation?

Steps 3 and 4 involve a decarboxylation. This is indicated by the evolution of CO2 in that step.

Electron Transport Chain:

What are the two mobile electron carriers in the ETC?

Complexes I and II

to

Complex III

Which of the ten steps in the glycolysis pathway are not reversible during gluconeogenesis. What

else is noteworthy about these three steps?

Steps 1, 3, and 10 of glycolysis cannot be reversed during gluconeogenesis. These are also the steps that serve as regulation points in the glycolysis pathway.

Which of the ten steps of the glycolysis pathway involve an isomerization reaction?

Steps 2, 5, and 8 involve an isomerization.

Which of the ten steps of the glycolysis pathway involve the formation of a phosphate ester link?

Steps 1, 3, and 8 involve the formation of an phosphate ester link.

Which of the ten steps of the glycolysis pathway involve the formation of a phosphate anhydride

link? Be careful! Think about all the compounds involved.

Steps 6, 7, and 10 involve the formation of an phosphate anhydride link. [Making ATP from ADP involves the formation of a phosphate anhydride link.]

Why is pyruvate kinase inhibited by Acetyl Coenzyme A?.

Under aerobic condition, the pyruvate produced by pyruvate kinase is converted to Acetyl

Coenzyme A. The acetyl-CoA enters the citric acid cycle which results in the production of a

considerable amount of ATP. If acetyl-CoA is not being used, its concentration will increase.

There is no point in making more acetyl-CoA if it is not being used, so the production of

pyruvate is shut down until more acetyl-CoA is required.

Glycolysis oxidizes glucose to pyruvate. Energy is obtain from these oxidative processes.

But, under anaerobic conditions, pyruvate is reduced to lactate. What purpose is served by

this reduction?

In the absence of oxygen, nothing further can be done to obtain energy from the pyruvate and

the glycolysis pathway has produced a lot of NADH which also cannot be utilized without

+

+

Fructose is part of the glycolysis pathway, just convert to fructose6phosphate.

galactose is converted to glucose.

mannose is converted to fructose.