NUCLEOTIDE METABOLISM

Question 0

First purine derivative formed…

Answer 0

Inosine monophosphate (IMP)

Question 1

Adenine nucleotides are components of 3 major coenzymes:

Answer 1

NAD+, FAD, Coenzyme A

Question 2

Two products of IMP…

Answer 2

AMP and GMP

Question 3

The activated form of ribose-5-phosphate.

Answer 3

5-phosphoribosyl-1-pyrophosphate (PRPP)

Question 4

The enzyme needed to convert ribose-5-phosphate to PRPP.

Answer 4

PRPP synthetase

Question 5

How many high energy phosphate equivalents are needed for the synthesis of PRPP?

Answer 5

Two. The reaction releases AMP from its original ATP state.

Question 6

Major site of purine synthesis.

Answer 6

Liver

Question 7

The following are required to synthesize IMP EXCEPT:

A. One mole of CO2
B. Two moles of formate
C. Two moles of glutamine
D. Two moles of glycine

Answer 7

D. Two moles of glycine

Question 8

The primary requirement for the formation of GMP is _______, and AMP is ________.

Answer 8

ATP, GTP

Question 9

The rate limiting steps in purine biosynthesis are:

Answer 9

⭕️ Synthesis of PRPP

⭕️ Amidotransferase reaction

Question 10

The enzyme that catalyzes the second reaction in purine biosynthesis.

Answer 10

PRPP glutamyl amidotransferase

Question 11

Uric acid is insoluble and is excreted in the urine as _____________.

Answer 11

Sodium urate crystals

Question 12

The process in which free purine bases are reconverted to their corresponding nucleotides.

Answer 12

Phosphoribosylation

Question 13

This reaction is catalyzed by what enzyme:

Adenine + PRPP AMP + PPi

Answer 13

Adenosine phosphoribosyltransferase or APRT

Question 14

The following reactions are catalyzed but which enzyme of the salvage pathways:

Hypoxanthine + PRPP IMP + PPi
Guanine + PRPP GMP + PPi

Answer 14

Hypoxanthine-Guanine Phosphoribosyltransferase or HGPRT

Question 15

A critically important enzyme of purine salvage in rapidly dividing cells is…

Answer 15

Adenosine deaminase or ADA

Question 16

Deficiency in the enzyme that catalyzes the deamination of adenosine to inosine results in what disorder?

Answer 16

Severe combined immunodeficiency (SCID)

Question 17

The synthesis of AMP from IMP and the salvage of IMP via AMP catabolism have the net effect of….

Answer 17

Deamination of aspartate to fumarate

Question 18

This cycle is important in muscle cells.

Answer 18

Purine Nucleotide Cycle

Question 19

The muscle-specific isoenzyme of AMP deaminase, and deficiencies in this enzyme leads to post-exercise fatigue, cramping, and myalgias.

Answer 19

Myoadenylate deaminase

Question 20

The precipitation of urate maybe in the forms of:

Answer 20

⭕️ monosodium urate (MSU)

⭕️ calcium pyrophosphate dihydrate (CPPD)

Question 21

Allopurinol strongly inhibits…

Answer 21

Xanthine oxidase

Question 22

Results from the loss of functional HGPRT gene.

Answer 22

Lesch-Nyhan Syndrome

Question 23

The net effect in Severe Combined Immunodeficiency Disease.

Answer 23

Inhibit DNA synthesis

Question 24

Deficiency in glucose-6-phosphatase results in…

Answer 24

von Gierke disease

Question 25

The carbamoyl phosphate used for pyrimidine nucleotide synthesis is derived from ___________ and ___________.

Answer 25

Glutamine and bicarbonate

Question 26

Rate limiting enzyme of pyrimidine nucleotide biosynthesis..

Answer 26

Aspartate transcarbamoylase (ATCase)

Question 27

The pyrimidine ring is synthesized from ______________ and ____________.

Answer 27

Carbamoyl phosphate and aspartate

Question 28

N-donor of pyrimidine synthesis:

Answer 28

Glutamine

Question 29

TRUE or FALSE: Pyrimidines are attach to PRPP for synthesis.

Answer 29

FALSE. They attached after the synthesis.

Question 30

The first phosphorylation of UMP is catalyzed by:

Answer 30

Uridylate kinase

Question 31

The second phosphorylation of UMP is catalyzed by:

Answer 31

Ubiquitous nucleoside diphosphate kinase

Question 32

UTP is converted to CTP via CTP synthase through what process?

Answer 32

Amination

Question 33

dUMP is converted to dTMP via what enzyme?

Answer 33

Thymidylate synthase

Question 34

The action of dihydrofolate reductase is…

Answer 34

Regeneration of THF from DHF

Question 35

ATCase prefers _______ as a substrate and is localized in the _________.

Answer 35

Glutamine, Cytoplasm