Question 1

Which of the following is an intermediate in the conversion of AMP to uric acid but NOT an intermediate in the conversion of GMP to uric acid?

Accepted Answer

The answer of Which of the following is an intermediate...

Question 2

Marine invertebrates express enzymes that allow for the conversion of uric acid to NH₄₊.What is the correct order of the action of enzymes in this pathway? 1)Urate oxidase 2)Allantoicase 3)Urease 4)Allantoinase

Accepted Answer

The answer of Marine invertebrates express enzymes that allow for...

Question 3

During the biosynthesis of UMP from carbamoyl phosphate and aspartate,dihydroorotate is converted to which of the following compounds?

Accepted Answer

During the biosynthesis of UMP, dihydroorotate is converted to orotate by the enzyme dihydroorotate dehydrogenase.

Question 4

If a mutation of the decarboxylase enzyme that functions in the biosynthetic pathway of UMP caused the pathway to halt at that step,which of the following would no longer occur?

Accepted Answer

The answer of If a mutation of the decarboxylase enzyme...

Question 5

What enzymatic activity is NOT required during the biosynthesis of UMP from carbamoyl phosphate and aspartate?

Accepted Answer

The answer of What enzymatic activity is NOT required during...

Question 6

Place the steps converting GMP to uric acid in the correct order. 
A.Conversion to guanine
B.Conversion to guanosine
C.Conversion to xanthine
D.Conversion to uric acid

Accepted Answer

GMP is first converted to guanosine, then to guanine, followed by conversion to xanthine, and finally to uric acid.

Question 7

The conversion of adenosine to inosine is catalyzed by __________,which is deficient in __________.

Accepted Answer

The conversion of adenosine to inosine is catalyzed by adenosine deaminase, which is deficient in ADA-SCID (adenosine deaminase-deficient severe combined immunodeficiency). Lesch-Nyhan syndrome is caused by the deficiency of the enzyme HGPRT (hypoxanthine-guanine phosphoribosyltransferase) or by a defect in purine salvage pathways, which results in the overproduction of uric acid and neurological symptoms. Xanthine oxidase is involved in the purine degradation pathway and its deficiency leads to xanthinuria, but not to the conversion of adenosine to inosine. Purine nucleoside phosphorylase deficiency results in the accumulation of deoxyguanosine, not in the conversion of adenosine to inosine.

Question 8

Which of the following organisms would generate this compound?

Accepted Answer

The answer of Which of the following organisms would generate...

Question 9

Nonprimate mammals convert uric acid to allantoin.This reaction,catalyzed by urate oxidase,also generates which of the following products?

Accepted Answer

The conversion of uric acid to allantoin by urate oxidase generates hydrogen peroxide (H₂O₂) as a byproduct.

Question 10

The possibility of ADA-SCID is indicated by __________ than normal activity of __________.

Accepted Answer

ADA-SCID (Adenosine Deaminase Severe Combined Immunodeficiency) is characterized by lower than normal activity of adenosine deaminase, not higher.

Question 11

A person is carrying out in vitro synthesis of uric acid from GMP.He or she wants to include all substrates and enzymes necessary.All EXCEPT __________ should be included in the reaction mixture.

Accepted Answer

Adenosine deaminase is not necessary for the synthesis of uric acid from GMP. The other three enzymes, purine nucleoside phosphorylase, guanine deaminase, and xanthine oxidase, are all necessary for the conversion of GMP to uric acid.

Question 12

A nitrogen of a pyrimidine ring arises from which amino acid?

Accepted Answer

Aspartate provides one of the nitrogen atoms in the pyrimidine ring during its biosynthesis.

Question 13

Aspartate contains four carbons.If all are radioactively labeled,how many carbons of UMP will be radioactively labeled?

Accepted Answer

Aspartate is one of the precursors of UMP (uridine monophosphate). Aspartate has four carbon atoms, and if all of them are radioactively labeled, then three of those carbons will contribute to the formation of carbons in UMP. The fourth carbon will not be incorporated into UMP because it is used to form fumarate, another molecule in the pyrimidine synthesis pathway. Therefore, the correct answer is choice C) 3.

Question 14

An enzyme panel analysis of a patient reveals a lack of __________,which is an indication of Lesch-Nyhan syndrome.

Accepted Answer

Lesch-Nyhan syndrome is caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) enzyme.

Question 15

How many of the nitrogens in orotidine-  -monophosphate arise from glutamine?

Accepted Answer

The answer of How many of the nitrogens in orotidine-...

Question 16

Samples from a bird,reptile,amphibian,and primate were analyzed by Western blotting for the expression of allantoinase,the enzyme that converts allantoin to allantoic acid.Unfortunately the researcher forgot the order that the samples were loaded into the gel.Luckily,only a single sample indicated allantoinase.Which sample contained allantoinase?

Accepted Answer

Allantoinase is an enzyme found in amphibians, which is used to convert allantoin to allantoic acid.

Question 17

The conversion of hypoxanthine to IMP is catalyzed by __________,which is deficient in __________.

Accepted Answer

Hypoxanthine is converted to IMP by the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). A deficiency in HGPRT leads to Lesch-Nyhan syndrome.

Question 18

Which of the following is the precursor of the indicated carbon atom in a pyrimidine ring?

Accepted Answer

The indicated carbon atom in a pyrimidine ring is derived from carbamoyl phosphate. This is the starting material for pyrimidine biosynthesis, and is converted into carbamoyl aspartate, which is then incorporated into the pyrimidine ring through a series of enzymatic reactions. Aspartate, glycine, and orotate are all intermediate or end products of this pathway, but are not the direct precursor of the indicated carbon atom.

Question 19

If GMP radiolabeled at the nitrogen atom indicated by the * were metabolized to uric acid,which of the following molecules along the pathway would also be radioactive?

Accepted Answer

The answer of If GMP radiolabeled at the nitrogen atom...

Question 20

Uric acid is processed to allantoic acid,which is then secreted.In which of the following organisms does this occur?

Accepted Answer

Bony fish convert uric acid to allantoic acid, which is then excreted.

Quiz 18: Nucleotide Metabolism

Which of the following is an intermediate in the conversion of AMP to uric acid but NOT an intermediate in the conversion of GMP to uric acid?

Marine invertebrates express enzymes that allow for the conversion of uric acid to NH₄₊.What is the correct order of the action of enzymes in this pathway? 1) Urate oxidase 2) Allantoicase 3) Urease 4) Allantoinase

During the biosynthesis of UMP from carbamoyl phosphate and aspartate,dihydroorotate is converted to which of the following compounds?

If a mutation of the decarboxylase enzyme that functions in the biosynthetic pathway of UMP caused the pathway to halt at that step,which of the following would no longer occur?

What enzymatic activity is NOT required during the biosynthesis of UMP from carbamoyl phosphate and aspartate?

Place the steps converting GMP to uric acid in the correct order. A.Conversion to guanine B.Conversion to guanosine C.Conversion to xanthine D.Conversion to uric acid

The conversion of adenosine to inosine is catalyzed by ,which is deficient in .

Which of the following organisms would generate this compound?

Nonprimate mammals convert uric acid to allantoin.This reaction,catalyzed by urate oxidase,also generates which of the following products?

The possibility of ADA-SCID is indicated by than normal activity of .

A person is carrying out in vitro synthesis of uric acid from GMP.He or she wants to include all substrates and enzymes necessary.All EXCEPT __________ should be included in the reaction mixture.

A nitrogen of a pyrimidine ring arises from which amino acid?

Aspartate contains four carbons.If all are radioactively labeled,how many carbons of UMP will be radioactively labeled?

An enzyme panel analysis of a patient reveals a lack of __________,which is an indication of Lesch-Nyhan syndrome.

How many of the nitrogens in orotidine- -monophosphate arise from glutamine?

The conversion of hypoxanthine to IMP is catalyzed by ,which is deficient in .

Which of the following is the precursor of the indicated carbon atom in a pyrimidine ring?

If GMP radiolabeled at the nitrogen atom indicated by the * were metabolized to uric acid,which of the following molecules along the pathway would also be radioactive?

Uric acid is processed to allantoic acid,which is then secreted.In which of the following organisms does this occur?

Quiz 18: Nucleotide Metabolism

Which of the following is an intermediate in the conversion of AMP to uric acid but NOT an intermediate in the conversion of GMP to uric acid?

Marine invertebrates express enzymes that allow for the conversion of uric acid to NH4+.What is the correct order of the action of enzymes in this pathway? 1) Urate oxidase 2) Allantoicase 3) Urease 4) Allantoinase

During the biosynthesis of UMP from carbamoyl phosphate and aspartate,dihydroorotate is converted to which of the following compounds?

If a mutation of the decarboxylase enzyme that functions in the biosynthetic pathway of UMP caused the pathway to halt at that step,which of the following would no longer occur?

What enzymatic activity is NOT required during the biosynthesis of UMP from carbamoyl phosphate and aspartate?

Place the steps converting GMP to uric acid in the correct order. A.Conversion to guanine B.Conversion to guanosine C.Conversion to xanthine D.Conversion to uric acid

The conversion of adenosine to inosine is catalyzed by __________,which is deficient in __________.

Which of the following organisms would generate this compound?

Nonprimate mammals convert uric acid to allantoin.This reaction,catalyzed by urate oxidase,also generates which of the following products?

The possibility of ADA-SCID is indicated by __________ than normal activity of __________.

A person is carrying out in vitro synthesis of uric acid from GMP.He or she wants to include all substrates and enzymes necessary.All EXCEPT __________ should be included in the reaction mixture.

A nitrogen of a pyrimidine ring arises from which amino acid?

Aspartate contains four carbons.If all are radioactively labeled,how many carbons of UMP will be radioactively labeled?

An enzyme panel analysis of a patient reveals a lack of __________,which is an indication of Lesch-Nyhan syndrome.

How many of the nitrogens in orotidine- -monophosphate arise from glutamine?

The conversion of hypoxanthine to IMP is catalyzed by __________,which is deficient in __________.

Which of the following is the precursor of the indicated carbon atom in a pyrimidine ring?

If GMP radiolabeled at the nitrogen atom indicated by the * were metabolized to uric acid,which of the following molecules along the pathway would also be radioactive?

Uric acid is processed to allantoic acid,which is then secreted.In which of the following organisms does this occur?

Marine invertebrates express enzymes that allow for the conversion of uric acid to NH₄₊.What is the correct order of the action of enzymes in this pathway? 1) Urate oxidase 2) Allantoicase 3) Urease 4) Allantoinase

The conversion of adenosine to inosine is catalyzed by ,which is deficient in .

The possibility of ADA-SCID is indicated by than normal activity of .

The conversion of hypoxanthine to IMP is catalyzed by ,which is deficient in .