Carbon Skeletons

Question 1

After an amino acid has lost its amino group through a transamination reaction, all that remains is the carbon skeleton (which is a keto acid).

What is the difference between a glucogenic and a ketogenic amino acid?

Answer 1

Glucogenic amino acids: the carbon skeletons of glucogenic amino acids can be converted into glucose

Ketogenic amino acids: the carbon skeletons of ketogenic amino acids can be converted into ketone bodies

Question 2

What metabolic reactions can glucogenic carbon skeletons be used in? How can the glucogenic carbon skeleton be converted into glucose?

Answer 2

Glucogenic carbon skeletons such as oxaloacetate can be used in the citric acid cycle. Oxaloacetate can also be converted into pyruvate. Once in the form of pyruvate, gluconeogenesis can be used to convert pyruvate into glucose.

Question 3

What metabolic reactions can ketogenic carbon skeletons be used in? How can the ketogenic carbon skeleton be converted into ketone bodies?

Answer 3

Ketogenic carbon skeletons can easily be converted into either acetyl CoA or acetoacetyl CoA (can be converted into acetyl CoA).

The acetyl CoA created from ketogenic carbon skeletons can be used in the reactions that have acetyl CoA as the input, for example, the ketogenesis reaction that make ketone bodies.

The acetyl CoA can also be used to begin the CAC to start the central metabolic pathway.