Nucleotide metabolism

Question 1

DNase and RNase are secreted by this organ

Answer 1

Pancreas

Question 2

Intestinal epithelial cells have this enzyme that catalyzes:
Nucleotides + H2O → Nucleosides + Pi

Answer 2

Alkaline phosphatase

Question 3

Enzyme that catalyzes:
Ribose-5-P + ATP → PRPP + AMP

Answer 3

Phosphoribosyl pyrophosphate (PRPP) synthetase

Question 4

Inhibition of PRPP synthetase

Answer 4

Purine ribonucleotides (ADP/GDP)

Question 5

Enzyme that catalyzes:
PRPP + glutamine → 5-phosphoribosylamine (PRA) + glutamate

Answer 5

Glutamine-PRPP amidotransferase

Question 6

Nitrogen donor in purine biosynthesis

Answer 6

Glutamine

Question 7

Rate-limiting step of purine biosynthesis

Answer 7

Glutamine-PRPP amidotransferase

Question 8

Inhibition of Glutamine-PRPP amidotransferase

Answer 8

AMP, ADP, ATP, GMP, GDP, and GTP

Question 9

Activation of Glutamine-PRPP amidotransferase

Answer 9

PRPP

Question 10

2 carbon donor in purine biosynthesis

Answer 10

N10-formyl FH4 is donor

Question 11

Common precursor for AMP and GMP

Answer 11

IMP

Question 12

Enzyme that catalyzes:
IMP → XMP → GMP

Answer 12

IMP dehydrogenase

Question 13

Inhibition of IMP dehydrogenase

Answer 13

GMP

Question 14

Enzyme that catalyzes:
IMP → adenylosuccinate → AMP

Answer 14

Adenosuccinyl synthetase

Question 15

Inhibition of Adenosuccinyl synthetase

Answer 15

AMP

Question 16

Activated form of ribose-5-phosphate

Answer 16

PRPP

Question 17

Does purine biosynthesis involve the building of the ring or the sugar first?

Answer 17

Sugar
Purine ring is built stepwise on the sugar

Question 18

Pyrimidines are made from these 2 molecules

Answer 18

Carbamoyl phosphate
Aspartate

Question 19

Does pyrimidine biosynthesis involve the building of the ring or sugar first?

Answer 19

Base is synthesized first and then added to PRPP

Question 20

Molecule that is a branch point and can be involved in both purine and pyrimidine biosynthesis

Answer 20

PRPP

Question 21

Enzyme that catalyzes:
Glutamine + CO2 + 2ATP → Carbamoyl phosphate

Answer 21

Carbamoyl phosphate synthetase II (CPS II)

Question 22

Rate limiting step of pyrimidine biosynthesis

Answer 22

Carbamoyl phosphate synthetase II (CPS II)

Question 23

Inhibition of Carbamoyl phosphate synthetase II (CPS II)

Answer 23

UTP

Question 24

Activation of Carbamoyl phosphate synthetase II (CPS II)

Answer 24

PRPP

Question 25

CPS I is involved in this pathway

Answer 25

Urea cycle

Question 26

CPS II is involved in this pathway

Answer 26

Pyrimidine synthesis

Question 27

Source of nitrogen used by CPS I

Answer 27

NH4+

Question 28

Source of nitrogen used by CPS II

Answer 28

Glutamine

Question 29

Location of CPS I

Answer 29

Mitochondria

Question 30

Location of CPS II

Answer 30

Cytosol

Question 31

Activator of CPS I

Answer 31

N-acetyl-glutamate

Question 32

Activator of CPS II

Answer 32

PRPP

Question 33

Enzyme that catalyzes:
Carbamoyl phosphate + aspartate

Answer 33

Aspartate transcarbamoylase

Question 34

Enzyme that closes the ring in pyrimidine biosynthesis

Answer 34

Dihydroorotase

Question 35

Polypeptide that contains the first three enzymes of pyrimidine biosynthesis

Answer 35

CAD

Question 36

Enzyme that adds ribose-P in pyrimidine biosynthesis

Answer 36

UMP synthase

Question 37

2 enzymatic functions of the UMP synthase polypeptide

Answer 37

Orotate PRPP transferase
Orotidylic acid decarboxylase

Question 38

Enzyme that converts:
UMP → UDP → UTP

Answer 38

UMP kinase (specific), NDP kinase

Question 39

Enzyme that converts UTP to CTP

Answer 39

CTP synthetase

Question 40

CTP synthetase uses this as the N donor

Answer 40

Glutamine