Exam 17: Amino Acid Metabolism

Most green plants contain both nitrate reductase and nitrite reductase to reduce nitrogen oxides to ammonia.

Chorismate is a key branch-point intermediate in aromatic amino acid synthesis.

All 20 common amino acids are metabolized through the citric acid cycle by first being converted to either pyruvate or acetyl CoA.

In mammals, most amino acids undergo deamination in the .

The changes that occur in cells that lead to its death are called .

Which is not part of the synthesis reactions for histidine?

Which type of protein might have a very short half-life and be specifically targeted for degradation?

Which type of organisms can eliminate excess nitrogen by the direct excretion of ammonia?

Only growing and reproducing cells require a continuous supply of amino acids for the synthesis of new protein molecules.

is hydrolytically cleaved to directly yield urea in the urea cycle.

Phenylalanine hydroxylase requires molecular and tetrahydrobiopterin.

A large percentage of nitrogen, undergoing metabolism, comes from nitrogen fixation.

Ammonia is incorporated into amino acids via which of the following?

Oxaloacetate is the amino-group acceptor in the synthesis of aspartate.

Because they lack aspartate kinase and aspartate semialdehyde dehydrogenase, cannot synthesize lysine, methionine or threonine.

Nitric oxide is a very reactive compound. In vivo it reacts with oxygen and water to form nitrates and nitrites within seconds.

If an amino acid is glucogenic, it will not be degraded to .

During the catabolism of amino acids, the carbon skeleton is first degraded, followed by the removal of the amino group.

How many ATP are consumed in the conversion of bicarbonate to carbamoyl phosphate?

Nitrogen fixation may occur via all of the following bacteria, except