Question 1

Lesch-Nyhan syndrome,a result of hypoxanthine-guanine phosphoribosyltransferase deficiency,there is a(n)________.

Accepted Answer

A) accumulation of hypoxanthine 
B) accumulation of GMP 
C) complete breakdown of purine biosynthesis 
D) excess of degradation of IMP and GMP 
E) accumulation of IMP 
A) accumulation of hypoxanthine 
B) accumulation of GMP 
C) complete breakdown of purine biosynthesis 
D) excess of degradation of IMP and GMP 
E) accumulation of IMP D

Question 2

Which is the precursor of all pyrimidine ribo- and deoxyribonucleotides?

Accepted Answer

A) dTMP. 
B) CTP. 
C) IMP. 
D) UMP. 
A) dTMP. 
B) CTP. 
C) IMP. 
D) UMP. D

Question 3

Modified nucleotides are rare and have not been shown to play significant roles in cell processes.

Accepted Answer

A) True 
 B)False  False

Question 4

Allantoin is the major end product of purine degradation in most mammals.

Accepted Answer

A) True 
 B)False

Question 5

The pyrimidine ring system is shown below.What is the source of the carbons 4,5 and 6 during the de novo biosynthesis of pyrimidines?

Accepted Answer

A) Glutamine. 
B) Aspartate. 
C) 3 bicarbonate ions. 
D) Pyruvate. 
A) Glutamine. 
B) Aspartate. 
C) 3 bicarbonate ions. 
D) Pyruvate.

Question 6

Purines and pyrimidines formed during digestion of food are more likely to be salvaged than those formed inside the cell.

Accepted Answer

A) True 
 B)False

Question 7

In eukaryotes all enzymes for the biosynthesis of the pyrimidine nucleotides occur exclusively in the cytosol.

Accepted Answer

A) True 
 B)False

Question 8

Which amino acid is not directly involved in the de novo biosynthesis of purines?

Accepted Answer

A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine. 
A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine.

Question 9

Enzymes that synthesize UMP are located on both sides of the mitochondrion in eukaryotic cells.

Accepted Answer

A) True 
 B)False

Question 10

The source of the hydrogen to form water during the reduction of nucleoside triphosphates is ________.

Accepted Answer

A) thioredoxin 
B) NADP 
C) NADH 
D) NADPH 
E)  FADH₂ 
A) thioredoxin 
B) NADP 
C) NADH 
D) NADPH 
E)  FADH₂

Question 11

The cofactor,methylenetetrahydrofolate,can donate a variety of one-carbon groups as well as act as a reducing agent in biochemical reactions.

Accepted Answer

A) True 
 B)False

Question 12

Eukaryotic cells maintain the correct balance of deoxyribonucleotides needed in a species DNA by ________.

Accepted Answer

A) controlling the activity of ribonucleotide reductase 
B) controlling the specificity of ribonucleotide reductase 
C) controlling both the specificity and activity of ribonucleotide reductase at the same time 
D) feedback inhibition 
E) controlling the balance of NADPH formed 
A) controlling the activity of ribonucleotide reductase 
B) controlling the specificity of ribonucleotide reductase 
C) controlling both the specificity and activity of ribonucleotide reductase at the same time 
D) feedback inhibition 
E) controlling the balance of NADPH formed

Question 13

Which structure below is PRPP?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 14

The purine ring system is shown below.What is the source of the N-1 atom during de novo biosynthesis of purines?

Accepted Answer

A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine. 
A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine.

Question 15

Four of the ten enzymes required for the biosynthesis of IMP are listed below.In which order do the reactions these enzymes catalyze occur during the synthesis of IMP? 
1.IMP cyclohydrolase
2.GAR synthase
3.glutamine-PRPP amidotransferase
4.AIR carboxylase

Accepted Answer

A) 1 → 2 → 3 → 4 
B) 4 → 3 → 2 → 1 
C) 3 → 2 → 4 → 1 
D) 2 → 3 → 4 → 1 
A) 1 → 2 → 3 → 4 
B) 4 → 3 → 2 → 1 
C) 3 → 2 → 4 → 1 
D) 2 → 3 → 4 → 1

Question 16

High levels of ________ will almost totally inhibit ATCase.

Accepted Answer

A) CTP 
B) ATP 
C) CTP and UTP 
D) ADP and UDP 
A) CTP 
B) ATP 
C) CTP and UTP 
D) ADP and UDP

Question 17

Which is the source of the ribose ring in purine nucleotides?

Accepted Answer

A) ATP. 
B) AMP. 
C) PRPP. 
D) cGDP. 
A) ATP. 
B) AMP. 
C) PRPP. 
D) cGDP.

Question 18

The purine ring system is shown below.What is the source of the atoms 5 and 7 during de novo biosynthesis of purines?

Accepted Answer

A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine. 
A) Glycine. 
B) Glutamine. 
C) Aspartate. 
D) Arginine.

Question 19

The conversion of UTP to CTP involves ________.

Accepted Answer

A) hydrolysis of a phosphate group 
B) oxidation of an OH group 
C) transfer of an NH₂ group 
D) formation of a carbon-carbon double bond 
A) hydrolysis of a phosphate group 
B) oxidation of an OH group 
C) transfer of an NH₂ group 
D) formation of a carbon-carbon double bond

Question 20

The action of the enzyme urease on urea produces ________.Urease is found in ________.

Accepted Answer

A) uracil;plants only 
B) uracil;all eukaryotes 
C) ammonia;all organisms 
D) ammonia;plants,crustaceans and some marine invertebrates 
A) uracil;plants only 
B) uracil;all eukaryotes 
C) ammonia;all organisms 
D) ammonia;plants,crustaceans and some marine invertebrates

Exam 18: Nucleotide Metabolism

Lesch-Nyhan syndrome,a result of hypoxanthine-guanine phosphoribosyltransferase deficiency,there is a(n)________.

Which is the precursor of all pyrimidine ribo- and deoxyribonucleotides?

Modified nucleotides are rare and have not been shown to play significant roles in cell processes.

Allantoin is the major end product of purine degradation in most mammals.

The pyrimidine ring system is shown below.What is the source of the carbons 4,5 and 6 during the de novo biosynthesis of pyrimidines?

Purines and pyrimidines formed during digestion of food are more likely to be salvaged than those formed inside the cell.

In eukaryotes all enzymes for the biosynthesis of the pyrimidine nucleotides occur exclusively in the cytosol.

Which amino acid is not directly involved in the de novo biosynthesis of purines?

Enzymes that synthesize UMP are located on both sides of the mitochondrion in eukaryotic cells.

The source of the hydrogen to form water during the reduction of nucleoside triphosphates is ________.

The cofactor,methylenetetrahydrofolate,can donate a variety of one-carbon groups as well as act as a reducing agent in biochemical reactions.

Eukaryotic cells maintain the correct balance of deoxyribonucleotides needed in a species DNA by ________.

Which structure below is PRPP?

The purine ring system is shown below.What is the source of the N-1 atom during de novo biosynthesis of purines?

Four of the ten enzymes required for the biosynthesis of IMP are listed below.In which order do the reactions these enzymes catalyze occur during the synthesis of IMP? 1.IMP cyclohydrolase 2.GAR synthase 3.glutamine-PRPP amidotransferase 4.AIR carboxylase

High levels of ________ will almost totally inhibit ATCase.

Which is the source of the ribose ring in purine nucleotides?

The purine ring system is shown below.What is the source of the atoms 5 and 7 during de novo biosynthesis of purines?

The conversion of UTP to CTP involves ________.

The action of the enzyme urease on urea produces ________.Urease is found in ________.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Protein Synthesis

Filters

The action of the enzyme urease on urea produces .Urease is found in .