Question 1

What are advantages of high urate levels such as those found in higher primates (like humans)?

Accepted Answer

Urate is a highly effective scavenger of reactive oxygen species (ROS).Urate is about as effective as ascorbate (vitamin C)as an antioxidant.Thus,high levels of urate may prevent cancer development and prolong life span in higher primates.

Question 2

What is the disadvantage of methotrexate as a therapeutic agent?

Accepted Answer

It kills all rapidly growing cells,so it causes severe side effects.Cells that are vulnerable include stem cells,certain epithelial cells,and hair follicles.This accounts for the hair loss,nausea,and loss of immune system protection during methotrexate therapy.

Question 3

The enzyme that catalyzes the generalized equation XDP + YTP $\rarr$ XTP + YDP is _________.

Accepted Answer

nucleoside diphosphate kinase

Question 4

TMP is made from

Accepted Answer

A)  dTMP. 
B)  UTP. 
C)  CTP. 
D)  ATP. 
E)  None of the answers is correct. 
A)  dTMP. 
B)  UTP. 
C)  CTP. 
D)  ATP. 
E)  None of the answers is correct.

Question 5

Given the function of nucleotides,would you expect their synthesis to be simple or complex and diverse?

Accepted Answer

Simple,as these molecules were important

Question 6

In ______________ biosynthesis,the base is assembled first and then attached to ribose.

Accepted Answer

The answer of In ______________ biosynthesis,the base is assembled first...

Question 7

Dihydrofolate reductase is an excellent target for anticancer drugs because it is critical in the synthesis of _______________.

Accepted Answer

The answer of Dihydrofolate reductase is an excellent target for...

Question 8

Inosinate can be converted to

Accepted Answer

A)  AMP. 
B)  GMP. 
C)  UMP. 
D)  CMP. 
E)  AMP or GMP. 
A)  AMP. 
B)  GMP. 
C)  UMP. 
D)  CMP. 
E)  AMP or GMP.

Question 9

Assembly of a compound from simpler molecules not salvaged from pre-existing similar molecules is known as a(n)_____ pathway.

Accepted Answer

A)  salvage 
B)  synthetic 
C)  catabolic 
D)  anabolic 
E)  de novo 
A)  salvage 
B)  synthetic 
C)  catabolic 
D)  anabolic 
E)  de novo

Question 10

Why do purine-salvage pathways save the cell energy?

Accepted Answer

Free purines can be attached to PRPP in

Question 11

Briefly describe,in one or two sentences,the reaction by which carbamoyl phosphate synthetase acquires an ammonia to make carbamoyl phosphate.

Accepted Answer

A polypeptide compon

Question 12

Which of the following is the methyl donor in the synthesis of dTMP from dUMP?

Accepted Answer

A)  N5-methyltetrahydrofolate 
B)  N5, N10-methylenetetrahydrofolate 
C)  S-adenosylmethionine 
D)  methylcobalamin 
E)  None of the answers is correct. 
A)  N5-methyltetrahydrofolate 
B)  N5, N10-methylenetetrahydrofolate 
C)  S-adenosylmethionine 
D)  methylcobalamin 
E)  None of the answers is correct.

Question 13

All of the nitrogen atoms found in nucleotides are ultimately derived from

Accepted Answer

A)  aspartate. 
B)  glutamine. 
C)  glycine. 
D)  asparagine. 
E)  aspartate and glutamine. 
A)  aspartate. 
B)  glutamine. 
C)  glycine. 
D)  asparagine. 
E)  aspartate and glutamine.

Question 14

In the de novo synthesis of DNA and RNA,

Accepted Answer

A)  ribonucleotides are made from deoxynucleotides. 
B)  deoxyribonucleotides are made from ribonucleotides. 
C)  dideoxyribonucleotides are the precursors for both. 
D)  ribonucleotides and deoxyribonucleotides are made by independent pathways. 
E)  None of the answers is correct. 
A)  ribonucleotides are made from deoxynucleotides. 
B)  deoxyribonucleotides are made from ribonucleotides. 
C)  dideoxyribonucleotides are the precursors for both. 
D)  ribonucleotides and deoxyribonucleotides are made by independent pathways. 
E)  None of the answers is correct.

Question 15

Assembly of a nucleoside from PRPP and a pre-existing base is known as a(n)_____ pathway.

Accepted Answer

A)  salvage 
B)  synthetic 
C)  catabolic 
D)  anabolic 
E)  de novo 
A)  salvage 
B)  synthetic 
C)  catabolic 
D)  anabolic 
E)  de novo

Question 16

What reaction actually forms the six-member ring found in pyrimidines?

Accepted Answer

The reaction between carbamoyl phosphate

Question 17

The conversion of ribonucleotides to deoxyribonucleotides is catalyzed by ________________.

Accepted Answer

ribonucleo

Question 18

The displacing nucleophile in pyrimidine synthesis is typically

Accepted Answer

A)  ammonia or an amino group. 
B)  a metal ion. 
C)  coenzyme A. 
D)  pyridoxamine. 
E)  None of the answers is correct. 
A)  ammonia or an amino group. 
B)  a metal ion. 
C)  coenzyme A. 
D)  pyridoxamine. 
E)  None of the answers is correct.

Question 19

What is a general theme in purine ring synthesis,in terms of reaction logic and mechanism?

Accepted Answer

The first six steps are similar in that

Question 20

Scaffolds on which the ring systems in nucleotides are assembled are the amino acids glycine and _______________.

Accepted Answer

The answer of Scaffolds on which the ring systems in...

Exam 25: Nucleotide Biosynthesis

What are advantages of high urate levels such as those found in higher primates (like humans)?

What is the disadvantage of methotrexate as a therapeutic agent?

The enzyme that catalyzes the generalized equation XDP + YTP →\rarr→ XTP + YDP is _________.

TMP is made from

Given the function of nucleotides,would you expect their synthesis to be simple or complex and diverse?

In ______________ biosynthesis,the base is assembled first and then attached to ribose.

Dihydrofolate reductase is an excellent target for anticancer drugs because it is critical in the synthesis of _______________.

Inosinate can be converted to

Assembly of a compound from simpler molecules not salvaged from pre-existing similar molecules is known as a(n)_____ pathway.

Why do purine-salvage pathways save the cell energy?

Briefly describe,in one or two sentences,the reaction by which carbamoyl phosphate synthetase acquires an ammonia to make carbamoyl phosphate.

Which of the following is the methyl donor in the synthesis of dTMP from dUMP?

All of the nitrogen atoms found in nucleotides are ultimately derived from

In the de novo synthesis of DNA and RNA,

Assembly of a nucleoside from PRPP and a pre-existing base is known as a(n)_____ pathway.

What reaction actually forms the six-member ring found in pyrimidines?

The conversion of ribonucleotides to deoxyribonucleotides is catalyzed by ________________.

The displacing nucleophile in pyrimidine synthesis is typically

What is a general theme in purine ring synthesis,in terms of reaction logic and mechanism?

Scaffolds on which the ring systems in nucleotides are assembled are the amino acids glycine and _______________.

Biochemistry: An Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

Oxidative Phosphorylation

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, repair, and Recombination

RNA Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

The enzyme that catalyzes the generalized equation XDP + YTP $\rarr$ XTP + YDP is _________.