Biochemistry Nucleotide Metab.

Front 1

Purines?

Back 1

adenine
guanine
hypoxanthine
xanthine

Front 2

Pyrimidines?

Back 2

cytosine
uracil
thymine
orotic acid

Front 3

What is hypoxanthine's nucleoside?

Back 3

inosine

Front 4

Functions of nucleotides?

Back 4

DNA and RNA polymer precursors
structural moieties of coenzymes
energy metabolism
ingredients of active metabolic precursors
physiological mediators
allosteric effectors of many metabolic enzymes

Front 5

Four coenzymes that use a nucleotide as a structural moiety?

Back 5

NADH
FAD
CoA
tetrahydrobiopterin

Front 6

How are dietary nucleotides converted to nucleosides?

Back 6

alkaline phosphatase

Front 7

How many ATPs are used in the synthesis of purine and pyrimidine?

Back 7

each use 6 ATP but purine does it in 11 steps while pyrimidine gets it done in 9

Front 8

What is defective in gout?

Back 8

de novo purine synthesis (g like guanine is a purine)

Front 9

What is defective in Lesch-Nyhan syndrome?

Back 9

purine salvage

Front 10

Defect in orotic aciduria?

Back 10

de novo pyrimidine synthesis

Front 11

Where does ribose 5-phosphate come from?

Back 11

glucose 6-phosphate via pentose phosphate pathway
or ribose 1-phosphate by nucleoside phosphorolysis

Front 12

How is PRPP synthesized?

Back 12

ribose 5-phosphate + ATP with PRPP synthetase

Front 13

Which reactions and pathways require PRPP?

Back 13

de novo synthesis and salvage purine AND pyrimidine pathways
NAD synthesis

Front 14

What is the first committed step in purine synthesis?

Back 14

Glutamine phosphoribosyl amidotransferase catalyzed conversion of PRPP + glutamine ->phosphoribosylamine

Front 15

Which enzyme is defective in Lesch-Nyhan?

Back 15

HGPRTase

Front 16

What does allopurinol inhibit?

Back 16

xanthine oxidase conversion of hypoxanthine to xanthine and xanthine to uric acid

Front 17

Where are all the enzymes for purine de novo synthesis found within the cell?

Back 17

cytosol

Front 18

How are deoxyribonucleotides formed?

Back 18

reduction of ribonucleoside 5'-diphosphates by ribonucleotide reductase

Front 19

What acts as a cofactor in the synthesis of deoxyribonucleotides?

Back 19

thioredoxin or glutaredoxin cofactors that help reduce ribose to deoxyribose

Front 20

What role does NADPH play in deoxyribonucleotide synthesis?

Back 20

reduces ribonucleotide reductase back to active form since it is oxidized in synthesis reaction

Front 21

What are the different classes of chemotherapeutic agents?

Back 21

antimetabolites
antifolates
glutamine antagonists
other compounds
antiviral agents

Front 22

How do antimetabolites act?

Back 22

structural analogs of bases or nucleosides so they interfere with specific sites of metabolism

Front 23

What are three antimetabolites?

Back 23

6-mercaptopurine
5-fluorouracil
cytosine arabinoside (araC)

Front 24

6-mercaptopurine?

Back 24

leukemia antitumor drug
purine analog that negatively effects PRPP amidotransferase of purine synthesis and neg effect on enzymes that make AMP and GMP from IMP

Front 25

5-fluorouracil?

Back 25

antitumor drug - pyrimidine analog
FUTP incorporates into RNA and stops maturation of 28S and 18S rRNA; and stops splicing of pre-mRNA
FdUMP inhibits thymidylate synthase

Front 26

cytosine arabinose?

Back 26

anti-leukemia cytidine analog
araCTP competes with dCTP in DNA polymerase reaction and when placed in DNA inhibits growth of strand

Front 27

What are antifolates?

Back 27

methotrexate (mtx)
inhibit formation of tetrahydrofolate by inhibiting dihydrofolate reductase

Front 28

Methotrexate?

Back 28

antitumor leukemia treatment; folate analog
inhibits dihydrofolate reductase thus depleting thymidine and purine nucleotides

Front 29

Which reactions do glutamine antagonists effect?

Back 29

amidation reactions using glutamine:
-de novo purine synthesis (N3 & N9)
-GMP synthesis from IMP
-cytosolic carbamoyl phosphate formation for pyrimidine synthesis
-CTP syntheis from UTP
-NAD synthesis

Front 30

Azaserine and 6-diazo-5-oxo-norleucine (DON)?

Back 30

antitumor glutamine analogs
inhibit enzymes that use glutamine as substrate
too toxic for clinical use

Front 31

cytosine arabinose?

Back 31

anti-leukemia cytidine analog
araCTP competes with dCTP in DNA polymerase reaction and when placed in DNA inhibits growth of strand

Front 32

What are antifolates?

Back 32

methotrexate (mtx)
inhibit formation of tetrahydrofolate by inhibiting dihydrofolate reductase

Front 33

Methotrexate?

Back 33

antitumor leukemia treatment; folate analog
inhibits dihydrofolate reductase thus depleting thymidine and purine nucleotides

Front 34

Which reactions do glutamine antagonists effect?

Back 34

amidation reactions using glutamine:
-de novo purine synthesis (N3 & N9)
-GMP synthesis from IMP
-cytosolic carbamoyl phosphate formation for pyrimidine synthesis
-CTP syntheis from UTP
-NAD synthesis

Front 35

Azaserine and 6-diazo-5-oxo-norleucine (DON)?

Back 35

antitumor glutamine analogs
inhibit enzymes that use glutamine as substrate
too toxic for clinical use

Front 36

Hydroxyurea?

Back 36

not an analog but inhibits ribonucleotide reductase to inhibit DNA synthesis but not RNA

Front 37

Tiazofurin?

Back 37

not an analog, has a ribose unit
inhibits IMP dehydrogenase, the limiting step in GTP synthesis

Front 38

Acyclovir (acycloguanosine)?

Back 38

antiviral against Herpes HSV
a purine base coupled with sugar analog
its triphosphate form is substrate for HSV-specific DNA polymerase so it stops DNA chain growth

Front 39

3'-azido-2'-deoxythymidine (AZT)?

Back 39

thymidine analog used against HIV
inhibits HIV-DNA polymerase which is RNA dependent
the host DNA polymerase is DNA dependent so much less sensitive