Exam 22: Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Draw the structure of 5'AMP.What is the first "committed" step in the biosynthetic sequence that leads to 5'AMP? How is this step regulated?

The amino acid that gives rise to the biological messenger NO is:

l-Dopa is an intermediate in the conversion of:

Show the reaction catalyzed by thymidylate synthase and explain with a simple diagram how the chemotherapeutic agents fluorouracil and methotrexate inhibit the synthesis of dTMP.

Give the equations for the two-step reaction sequence catalyzed by glutamine synthetase.

Why is it necessary to have protein in our (human)diets?

De novo purine biosynthesis is distinguished from de novo pyrimidine biosynthesis by:

Show the biosynthetic pathway for the conversion of a citric acid cycle intermediate into proline.Indicate where any cofactors participate.

The ribosyl phosphate moiety needed for the synthesis of orotidylate,inosinate,and guanylate is provided most directly by:

Glutathione is a(n):

An intermediate of purine degradation in humans is:

Precursors for the biosynthesis of the pyrimidine ring system include:

Azaserine is a structural analog of glutamine.It is a competitive inhibitor of many enzymes that use glutamine as substrates.Name)three biosynthetic products whose synthesis you would expect to be inhibited by azaserine.Do you think that eating azaserine would be immediately fatal? Why or why not?

Show the two-step reaction catalyzed by tryptophan synthetase.

Which of the following enzymes is not involved in the assimilation of inorganic nitrogen into an organic molecule?

An important intermediate in the biosynthetic pathway to aromatic amino acids is:

An amino acid that does not derive its carbon skeleton,at least in part,from $\alpha$ -ketoglutarate is:

Which of the following statements about the fixation of atmospheric nitrogen (N₂)into NH₃ by living cells is false?

Explain how lack of adenosine deaminase leads to a 100-fold increase in dATP,yet also causes a deficiency in dNTPs required for replication of T-cells and B-cells required for a functioning immune system.

Which of the following is not true about glutamine amidotransferases?