1. What is an essential amino acid? Which ones are they?
2. State the metabolites from which each nonessential amino acid is synthesized. These metabolites are found in glycolysis or the TCA cycle. One metabolite is an essential amino acid.
3. What is a glucogenic amino acid? Which pathways do their catabolic products enter?
4. What is a ketogenic amino acid? What are their catabolic products that are ketone bodies or intermediates in the pathway for ketone body synthesis?
5. For each amino acid, be able to say where its catabolic products enter the TCA cycle, the glycolytic/gluconeogenic pathways, and/or the ketone body pathway.
6. Name the cofactor produced from folic acid. What is the function of this cofactor? Describe the reaction in which serine and glycine are interconverted.
7. Name the reactants and products of each reaction in the conversion of serine to cysteine.
8. What are the products of the catabolism of cysteine?
9. What is the product of methionine degradation that is also a metabolite in the TCA cycle?
10. When does arginine become an essential amino acid? When is arginine not an essential amino acid?
11. Be able to state the components of the reaction that converts phenylalanine to tyrosine. What are the molecular causes of phenylketonuria?
12. Why is phenylketonuria not called phenylalanineuria? How are ketones formed?
13. Concerning Homer Sistine: If he had an inborn error in cystathionine synthase, what would happen to his concentrations of methionine, homocysteine, and cysteine? Why? If his problem had been a deficiency of folate or vitamin B12 , what would you expect to happen to the concentrations of methionine, homocysteine, and cysteine? Why?


α-ketobutryate, cystathionase, cystathionine, cystathionine synthase, cysteine, dihydrobiopterin, essential amino acid, FH4, glucogenic amino acids, glycine, homocysteine, homocyst(e)ine, hydroxylation, ketogenic amino acid, methionine, 5,10-methylene tetrahydrofolate, mixed function oxidase, phenylalanine, phenylalanine hydroxylase, phenylketoneuria, phenylpyruvate, PKU, pyruvate, serine, succinyl CoA, sulfate, tetrahydrobiopterin, tetrahydrofolate.


Understand the meaning of the key words in the context of Chapter 39.

Examine Questions (Q:) and Answers (A:) in Chapter 39.

Work Review Questions 1- 5 at the end of the Chapter 39 but not Questions 4.

Work the Practice Questions for Chapter 39 Objectives

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Ketogenic Amino Acids