CH 21

(ch26 dropbox #32) The pictured compound, glutamate-5-semialdehyde, is an intermediate in the biosynthesis of which of the following amino acids? (picture)

The lifetime of a protein in cells actively involved in metabolism

The aminotransferase reaction, in which an enzyme-PLP Schiff base forms,

I. is ATP dependent.
II. results in formation of a hydroxylaldehyde.
III. results in formation of an α-ketoacid.
IV. requires an active site lysine.

Fumarate from the urea cycle is converted to malate and then to ______ , which can be used for gluconeogenesis.

Glutamine synthetase is subject to feedback inhibition by which of the following chemicals?

Which of the following statements about maple syrup urine disease is FALSE?

I. It is caused by a genetic deficiency in the enzyme BCKDH.
II. The disease is fatal unless promptly treated.
III. There is a buildup of the branched-chain α-keto acids.
IV. Patients with the disease excrete urine that smells like maple syrup.

The total cost of nitrogen reduction is ____ and ___ transferred electrons.

Which of the following amino acids is NOT synthesized from aspartic acid?

In which cellular compartment does the following reaction take place?
ornithine + carbamoyl-phosphate —> citrulline

Nitrogenase

I. can be found in most bacteria and a few invertebrate animals.
II. contains unique redox centers that contain both Fe and Mo.
III. changes in conformation as a result of ATP hydrolysis.
IV. carries out a reaction that reduces nitrogen to NO.

Which of the following best describes the catabolism of lysine and leucine?

The metabolite chorismate

Which of the following statements about tryptophan synthase is FALSE?

Which of the following require a cyclic carbohydrate precursor for synthesis?

I. histidine
II. alanine
III. arginine
IV. tyrosine

The total cost of nitrogen reduction is 8 electrons and

In which cellular compartment does the following reaction take place?
arginine —> urea + ornithine

_____ catalyzes the synthesis of ____, a molecule that signals vasodilation, from the precursor _____

The neurotransmitters (DOPA), dopamine, epinephrine, and norepinephrine are synthesized from the amino acid

Which of the following are essential amino acids for adult humans?

The amino acids Ala, Cys, Gly, Ser, and Thr are all degraded to the metabolic intermediate ___ and are considered ____.

Which enzyme catalyses a reaction via an enzyme-bound adenylated intermediate?

Individuals with an alanine to valine mutation in N5, N10 – methylenetetrahydrofolate reductase (MTHFR)

I. typically have higher levels of homocysteine.
II. have increased risk for cardiovascular disease.
III. typically have increased incidence of oxidative damage to the walls of blood vessels.
IV. are at increased risk, if female, of giving birth to a child with a neural tube defect.

Which of the following is required for synthesis of tryptophan?

Enzyme A is involved in the metabolism of metabolite C to metabolite D. Enzyme A is part of a linear pathway involving ten enzymes ultimately converting B →F. High levels of F directly alter the activity of enzyme A and result in control over the overall pathway. Enzyme A

The amino acids Ala, Cys, Gly, Ser, and Thr are all degraded to the metabolite

The presence of SGOT and SGPT in the serum indicate potential

Ketogenic amino acids are broken down to acetoacetate or

The synthesis of which of the following uses an aminotransferase in the first step of the synthesis?

A number of compounds, including neurotransmitters, are synthesized from amino acids via decarboxylations. The enzymes catalyzing these steps usually use _______ as a cofactor.

When glutamate is oxidatively deaminated by GDH, the products include

A molecule that signals vasodilation is _____, which is synthesized from the precursor _____.

Which of the following control the urea cycle?

I. substrate concentration of the cycle enzymes
II. allosteric activation of carbamoyl phosphate synthetase I
III. concentration of glutamate
IV. availability of glucose

The metabolite chorismate

Which of the following statements about maple syrup urine disease is false?

Which of the following is TRUE about glutamine?

I. It is formed from α-ketoglutarate.
II. It donates an amino group to aspartate to form asparagine.
III. It is directly required for ornithine synthesis.
IV. It is a precursor to homoserine.

Which of the following glycolytic intermediates is the common precursor to serine, cysteine, and glycine?

What are KFERQ proteins?

I. Proteins that contain the KFERQ pentapeptide sequence (or a similar sequence) .
II. Proteins that are selectively degraded in tissues that atrophy after a prolonged fast (starvation).
III. A special set of enzymes that are activated in response to starvation.

What species are combined to produce carbamoyl phosphate?

Heme biosynthesis

Which of the following statements about phenylalanine is(are) TRUE?

Nitrogenase carries out the reaction that reduces nitrogen to

Which of the following amino acid breakdown reactions would be catalyzed by an aminotransferase?

Which of the following reaction sequences could result in glucose synthesis?

The majority of amino acids are deaminated by a ______ reaction.

Which of the following statements about phenylalanine is/are true?

The activity of bacterial glutamine synthetase is

I. inhibited allosterically by tryptophan.
II. inhibited allosterically by glucosamine-6-phosphate.
III. activated by nine allosteric feedback inhibitors.
IV. altered by covalent modification.

Heme biosynthesis

Ketogenic amino acids can be converted to

I. glucose
II. fatty acids
III. ketone bodies
IV. pyruvate

The aminotransferase reaction, in which an enzyme-PLP Schiff base forms, follows a(n) ______ kinetic mechanism.

A mutation in GDH of patients with HI/HA (hypoglycemia/hyperammonemia) results in a decrease in allosteric control of GDH via GTP. Which of the following will be observed in the patients?