Question 1

At its allosteric site, ribonucleotide reductase is

Accepted Answer

A)  inhibited by ATP and stimulated by dATP 
B)  inhibited by dATP and stimulated by ATP 
C)  inhibited by both ATP and dATP 
D)  stimulated by both ATP and dATP 
A)  inhibited by ATP and stimulated by dATP 
B)  inhibited by dATP and stimulated by ATP 
C)  inhibited by both ATP and dATP 
D)  stimulated by both ATP and dATP

Question 2

Defects in adenosine deaminase lead to increased ___ levels, which impact ribonucleotide reductase and further lead to ___ and SCID.

Accepted Answer

A)  dGTP, imbalance of dNTPs 
B)  dATP, imbalance of dNTPs 
C)  ATP, deficient metabolic energy 
D)  GTP, deficient cell signaling ability 
E)  ATP, imbalance of NTPs 
A)  dGTP, imbalance of dNTPs 
B)  dATP, imbalance of dNTPs 
C)  ATP, deficient metabolic energy 
D)  GTP, deficient cell signaling ability 
E)  ATP, imbalance of NTPs

Question 3

Dihydroorotate is synthesized from

Accepted Answer

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

Question 4

The common intermediate of purines AMP and GMP is __________, while the common intermediate of the pyrimidines cytosine, thymidine and uracil is ______.

Accepted Answer

The answer of The common intermediate of purines AMP and...

Question 5

Which of the following is formed as a result of pyrimidine metabolism?

Accepted Answer

A)  alanine 
B)  aspartate 
C)  asparagine 
D)  glycine 
E)  $\beta$-alanine 
A)  alanine 
B)  aspartate 
C)  asparagine 
D)  glycine 
E)  $\beta$-alanine

Question 6

What molecule is used to reduce ribonucleotide reductase back to its catalytically active state?

Accepted Answer

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

Question 7

Regulation of pyrimidine de novo synthesis in mammals is through allosteric control by

Accepted Answer

A)  aspartate transcarbamoylase (ATCase) 
B)  OMP decarboxylase 
C)  dihydroorotase dehydrogenase 
D)  hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) 
E)  ribose phosphate pyrophosphokinase 
A)  aspartate transcarbamoylase (ATCase) 
B)  OMP decarboxylase 
C)  dihydroorotase dehydrogenase 
D)  hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) 
E)  ribose phosphate pyrophosphokinase

Question 8

In general, as nucleotides are catabolized,

Accepted Answer

A)  dephosphorylation is followed by deglycosylation then bases undergo deamination/oxidation 
B)  deglycosylation is followed by dephosphorylation then bases undergo deamination/oxidation 
C)  bases undergo deamination/oxidation followed by deglycosylation, then dephosphorylation 
D)  bases undergo deamination/oxidation, followed by dephosphorylation then deglycosylation 
E)  dephosphorylation is followed by bases undergoing deamination/oxidation, then deglycosylation 
A)  dephosphorylation is followed by deglycosylation then bases undergo deamination/oxidation 
B)  deglycosylation is followed by dephosphorylation then bases undergo deamination/oxidation 
C)  bases undergo deamination/oxidation followed by deglycosylation, then dephosphorylation 
D)  bases undergo deamination/oxidation, followed by dephosphorylation then deglycosylation 
E)  dephosphorylation is followed by bases undergoing deamination/oxidation, then deglycosylation

Question 9

In purine biosynthesis, amination of PRPP and FGAR, through catalysis by amidophosphoribosyl transferase and formylglycinamide ribonucleotide synthetase, respectively, requires the amino acid

Accepted Answer

A)  glutamate 
B)  glycine 
C)  glutamine 
D)  alanine 
E)  aspartate 
A)  glutamate 
B)  glycine 
C)  glutamine 
D)  alanine 
E)  aspartate

Question 10

Ribonucleotide reductase relies on cofactors

Accepted Answer

A)  Fe or Mn 
B)  Mn or Mg 
C)  Cu or Mg 
D)  Cu 
E)  None of the above 
A)  Fe or Mn 
B)  Mn or Mg 
C)  Cu or Mg 
D)  Cu 
E)  None of the above

Question 11

Which of the following is correct regarding pyrimidine synthesis?

Accepted Answer

A)    
B)    
C)    
D)  A and C 
E)  None of the above 
A)    
B)    
C)    
D)  A and C 
E)  None of the above

Question 12

Having both regulatory and catalytic subunits, ribonucleotide reductase undergoes ___ control

Accepted Answer

The answer of Having both regulatory and catalytic subunits, ribonucleotide...

Question 13

What enzyme is responsible for the conversion of nucleotides to deoxynucleotides?

Accepted Answer

A)  ribonucleotide deoxidase 
B)  ribonucleotide dehydratase 
C)  ribonucleotide dehydrogenase 
D)  ribonucleotide oxidase 
E)  ribonucleotide reductase 
A)  ribonucleotide deoxidase 
B)  ribonucleotide dehydratase 
C)  ribonucleotide dehydrogenase 
D)  ribonucleotide oxidase 
E)  ribonucleotide reductase

Question 14

IMP synthesis from ribose-5-phosphate requires ___ ATP hydrolyses.

Accepted Answer

A)  2 
B)  4 
C)  6 
D)  8 
E)  10 
A)  2 
B)  4 
C)  6 
D)  8 
E)  10

Question 15

Which is NOT a strategy of ribonucleotide reductase to afford a proper balance of dNTPs for the cell? In general:

Accepted Answer

A)  adenosine nucleotides in the regulatory site $\rightarrow$ pyrimidine nucleotides recognized in the catalytic site 
B)  dGTP in the regulatory site $\rightarrow$ADP recognized in the catalytic site 
C)  dATP in the regulatory site $\rightarrow$ GDP recognized in the catalytic site 
D)  dTTP in the regulatory site $\rightarrow$GDP in the catalytic site 
E)  adenosine nucleotides in the regulatory site $\rightarrow$ varied subunit stoichiometries 
A)  adenosine nucleotides in the regulatory site $\rightarrow$ pyrimidine nucleotides recognized in the catalytic site 
B)  dGTP in the regulatory site $\rightarrow$ADP recognized in the catalytic site 
C)  dATP in the regulatory site $\rightarrow$ GDP recognized in the catalytic site 
D)  dTTP in the regulatory site $\rightarrow$GDP in the catalytic site 
E)  adenosine nucleotides in the regulatory site $\rightarrow$ varied subunit stoichiometries

Question 16

In the mechanism of ribonucleotide reductase, a _____ is generated at C3' to stabilize the _____ that is formed at C2'.

Accepted Answer

A)  radical; carbocation 
B)  radical; carbanion 
C)  carbocation; radical 
D)  carbanion; radical 
E)  carbanion; carbocation 
A)  radical; carbocation 
B)  radical; carbanion 
C)  carbocation; radical 
D)  carbanion; radical 
E)  carbanion; carbocation

Question 17

Active site ___ are important to carbocation mechanism of ribonucleotide reductase

Accepted Answer

A)  serines 
B)  aspartic acids 
C)  cysteines 
D)  NAD+ coenzymes 
E)  glutamines 
A)  serines 
B)  aspartic acids 
C)  cysteines 
D)  NAD+ coenzymes 
E)  glutamines

Question 18

The precursor to AMP and GMP is ______.

Accepted Answer

The answer of The precursor to AMP and GMP is...

Question 19

Which of the following amino acids is a source of both carbon and nitrogen for IMP?

Accepted Answer

A)  Glu 
B)  Gln 
C)  Gly 
D)  Asp 
E)  Asn 
A)  Glu 
B)  Gln 
C)  Gly 
D)  Asp 
E)  Asn

Question 20

What nucleotide is methylated to produce dTMP?

Accepted Answer

A)  dAMP 
B)  dCMP 
C)  dGMP 
D)  dUMP 
E)  both dCMP and dUMP can be converted to dTMP 
A)  dAMP 
B)  dCMP 
C)  dGMP 
D)  dUMP 
E)  both dCMP and dUMP can be converted to dTMP

Exam 13: Nucleotide Deoxynucleotide Metabolism

At its allosteric site, ribonucleotide reductase is

Defects in adenosine deaminase lead to increased ___ levels, which impact ribonucleotide reductase and further lead to ___ and SCID.

Dihydroorotate is synthesized from

The common intermediate of purines AMP and GMP is __________, while the common intermediate of the pyrimidines cytosine, thymidine and uracil is ______.

Which of the following is formed as a result of pyrimidine metabolism?

What molecule is used to reduce ribonucleotide reductase back to its catalytically active state?

Regulation of pyrimidine de novo synthesis in mammals is through allosteric control by

In general, as nucleotides are catabolized,

In purine biosynthesis, amination of PRPP and FGAR, through catalysis by amidophosphoribosyl transferase and formylglycinamide ribonucleotide synthetase, respectively, requires the amino acid

Ribonucleotide reductase relies on cofactors

Which of the following is correct regarding pyrimidine synthesis?

Having both regulatory and catalytic subunits, ribonucleotide reductase undergoes ___ control

What enzyme is responsible for the conversion of nucleotides to deoxynucleotides?

IMP synthesis from ribose-5-phosphate requires ___ ATP hydrolyses.

Which is NOT a strategy of ribonucleotide reductase to afford a proper balance of dNTPs for the cell? In general:

In the mechanism of ribonucleotide reductase, a _____ is generated at C3' to stabilize the _____ that is formed at C2'.

Active site ___ are important to carbocation mechanism of ribonucleotide reductase

The precursor to AMP and GMP is ______.

Which of the following amino acids is a source of both carbon and nitrogen for IMP?

What nucleotide is methylated to produce dTMP?

The Chemical Foundations of Biochemistry

Nucleic Acids

Proteins I

Proteins Iienzymes

Membranes and an Introduction to Signal Transduction

Carbohydrates I

The Common Catabolic Pathway

Carbohydrates II

Lipids I

Lipids II

Amine Metabolism

Metabolism Integration

Dna Replication, Damage and Repair

Rna Synthesis

Protein

Control of Gene

Determination of Macromolecular Structure

Allosterism and Receptor-Ligand

Designer Proteins and Protein Folding

Biomolecule Purification

Bioinformatics and Omics

Signal

Protein Trafficking

Photosynthesis Nitrogen

Filters

Defects in adenosine deaminase lead to increased _ levels, which impact ribonucleotide reductase and further lead to _ and SCID.

The common intermediate of purines AMP and GMP is ____, while the common intermediate of the pyrimidines cytosine, thymidine and uracil is .

In the mechanism of ribonucleotide reductase, a _ is generated at C3' to stabilize the _ that is formed at C2'.