Nucleotide Metabolism

Question 1

When you synthesize common new nucleotides

Answer 1

de novo synthesis

Question 2

What is the purine ring precursor?

Answer 2

hypoxanthine (a nitrogenous base)

Question 3

What is the pyrimidine ring precursor?

Answer 3

Oroate (a nitrogenous base and carboxylic acid)

Question 4

T/F: While purine precursor is

directly synthesized on ribose C-1, the pyrimidine is synthesized stepwise then attached to the ribose C-1

Answer 4

T

Question 5

Precursors hypoxanthine and orotate are coupled with

Answer 5

5-phosphoribosyl-1-pyrophosphate (PRPP)

Question 6

Synthesis of PRPP requires what enzyme?

Answer 6

PRPP synthetase

Question 7

PRPP (1-pyrophosphate) activated C1 on what sugar?

Answer 7

Ribose

Question 8

PRPP is a key substrate in both a ____ and ____ synthesis

Answer 8

purine and pyrimidine

Question 9

Is synthesis of PRPP a committed step or not

Answer 9

no, it creates 2 different substrates

Question 10

During ____ synthesis, a 5 membered ring is built on PRPP first

Answer 10

purine

Question 11

Methyl groups in the formation of purine come from

Answer 11

N10-formyl-tetrahydro-folate

Question 12

T/F: In purine synthesis, methyl groups come from SAM

Answer 12

False, they comes from N10-formyl-tetrahydro-folate

Question 13

AMP and GMP are made from

Answer 13

IMP

Question 14

The precursor for Adenylate (AMP) and Guanylate (GMP) is

Answer 14

Inositate IMP

Question 15

You use ____ (ATP/GTP) when synthesizing adenylate, and ____(ATP/GTP) when synthesizing Guanylate

Answer 15

GTP, ATP

Question 16

When making adenylate, your nitrogen donating group is ____

Answer 16

Aspartate

Question 17

When making guanylate you use what a nitrogen donating group?

Answer 17

Glutamine (Gln)

Question 18

During de novo pyrimidine biosynthesis, the first step is

Answer 18

formation of carbamoyl phosphate

Question 19

Glutamine can be turned into glutamate using what enzyme?

Answer 19

carbamoyl phosphate synthetase II

Question 20

The formation of carbamoyl phosphate and glutamate occurs in the (cytoplasm/mitochondria), which is different from the urea cycle which takes place in the (cytoplasm/mitochondria)

Answer 20

cytoplasm, mitochondria

Question 21

In the formation of carbamoyl phosphate, nitrogen is taken from _____ but int he urea cycle, the nitrogen is taken from _____ released from glutamine

Answer 21

glutamine, ammonia

Question 22

The formation of N-carbamoylaspartate is catalyzed by what enzyme?

Answer 22

aspartate transcarbamoylase

Question 23

The committed step of pyrimidine is what?

Answer 23

The second step

he formation of N-carbamoylaspartate is catalyzed by aspartate transcarbamoylase

Question 24

The feedback of turning aspartate into N-carbamoylaspartate is inhibited by

Answer 24

CTP (cytidine 5’-triphosphate)

Question 25

These three components come together to produce what compound? Glutamine, HCO3-, Aspartate

Answer 25

N-Carbamoylaspartate

Question 26

Nucleoside diphosphate turns to deoxyribonucleoside diphosphate using what enzyme? What is its energy source?

Answer 26

ribonucleotide reductase NADPH from Pentose phosphate pathway

Question 27

What is dihydrofolate reductase inhibited by?

Answer 27

Methotrexate Aminopterin Trimethoprim

Question 28

When going from dTMP to dUMP, what enzyme do we use?

Answer 28

Thymidylate synthase

Question 29

When going from dTMP to dUMP, the methyl group donator is the____. What is its energy source?

Answer 29

N5N10 methylete-THF, NADPH

Question 30

Regeneration of N5N10 methylene-THF happens by

Answer 30

dihydrofolate reductase & serine-hydroxymethyl tra

Question 31

Guanine and hypoxanthine are formed from what in the salvage pathway of purine synthesis

Answer 31

adenine

Question 32

Hypoxanthine + PRPP = what

Answer 32

IMP

Question 33

Guanine + PRPP = what

Answer 33

GMP

Question 34

Adenine + PRPP = what

Answer 34

AMP

Question 35

ADA deficiency causes what

Answer 35

SCID

Question 36

XO (xanthine oxidase) inhibitors are a good treatment for what condition

Answer 36

gout

Question 37

Buildup of Uric Acid from AMP and GMP causes what disease?

Answer 37

Gout

Question 38

ADA (adenosine deaminase) stops the formation of ____ from ____

Answer 38

inosine, adenosine

Question 39

Xanthine Oxidase (XO) contributes ___ to uric acid

Answer 39

OH

Question 40

What type of autosomal disorder is Lesch-Nyhan Syndrome

Answer 40

Rare x-linked recessive disorder

Question 41

Lesch-Nyhan is caused by a complete lack of

Answer 41

HGPRT

Question 42

In Lesch-Nyhan, the brain becomes dependent on what pathway to produce nucleotides?

Answer 42

salvage pathway

Question 43

What two mechanisms can lead to elevated serum urate?

Answer 43

Hyperactive PRPP Synthetase and Partial lack of HGPRT

Question 44

Excess PRPP accelerates purine biosynthesis

Answer 44

Hyperactive PRPP synthetase

Question 45

Reduced salvage pathway; also leads to excess PRPP and accelerated purine synthesis

Answer 45

Partial lack of HGPRT

Question 46

Excess PRPP leads to

Answer 46

elevated serum urate, or gout