Nucleotides- De novo pathway

Question 1

metabolic precursors:

Answer 1

ribose-5-phosphate, amino acids,
CO2 and NH3

Question 2

are de novo pathways of nucleotide synthesis energetically expensive?

Answer 2

yes

Question 3

glycine is the precursor for purines or pyramidines?

Answer 3

purines

Question 4

aspartate is the precursor for purines or pyramidines?

Answer 4

pyramidines

Question 5

what are the two pathways of nucleotide synthesis?

Answer 5

de novo pathway and salvage pathways

Question 6

salvage pathway is when: free bases and nucleosides released from nucleic acid breakdown are ???

Answer 6

recycled

Question 7

PRPP (5-phosphoribosyl 1-pyrophosphate) is what the purine or pyramidine ring is assembled on?

Answer 7

purine ring

Question 8

in the first committed step of purine pathway, an amino acid is donated by ??? and attached to C-1 of PRPP ring

Answer 8

glutamine

Question 9

what is formed through the donation of an amino acid by glutamine to PRPP in comitment step 1 of purine synthesis?

Answer 9

5-phosphoribosylamine

Question 10

in the 2nd step of purine synthesis, 3 atoms are donated from ??? ATP is required for this step

Answer 10

glycine

Question 11

in higher eukaryotes, 10 steps are required in purine synthesis to form the ring structure and the nucleotide ???

Answer 11

inosinate (IMP)

Question 12

TRUE or FALSE: in purine synthesis, IMP is the first intermediate with a
complete purine ring

Answer 12

TRUE

Question 13

TRUE or FALSE: Inosinate forms a branch point in purine de novo pathway: can form adenylate (AMP) or Guanylate (GMP)

Answer 13

TRUE

Question 14

Conversion of IMP to Adenylate (AMP) requires an amino group from ???, requiring GTP

Answer 14

aspartate

Question 15

Conversion of IMP to GMP requires an amino group from ???, requiring ATP

Answer 15

glutamine

Question 16

the amount and availability of AMP, GMP, and IMP can inhibit the conversion of ??? to 5-phosphoribosylamine

Answer 16

PRPP

Question 17

AMP amounts can inhibit conversion of IMP to ???

Answer 17

AMP

Question 18

GMP amounts can inhibit conversion of IMP to ???

Answer 18

GMP

Question 19

the amount and availability of ATP can inhibit the conversion of ribose-5-phosphate to ???

Answer 19

PRPP

Question 20

Pyrimidine synthesis proceeds by first making the pyrimidine ring in the form of ???

Answer 20

orotate

Question 21

??? and carbamoyl phosphate provide the atoms for the ring structure, making synthesis of pyrimidine ring simpler than purine ring

Answer 21

Aspartate

Question 22

Ribose 5-phosphate is attached BEFORE or AFTER pyrimidine ring formation

Answer 22

AFTER

Question 23

Ribonucleotide reductase converts ??? to deoxyribonucleotides

Answer 23

ribonucleotides

Question 24

Thioredoxin acts as an ??? protein that carries a pair of H atoms, via –SH groups, from NADPH to the ribonucleoside diphosphate

Answer 24

intermediate hydrogen-carrying

Question 25

Thioredoxin reductase catalyses the reduction of the ??? form of thioredoxin by NADPH

Answer 25

oxidised

Question 26

Reduction of Ribonucleotides to Deoxyribonucleotides: Electrons and H+ are transmitted from ??? to ??? via glutaredoxin and thioredoxin

Answer 26

NADPH to ribonucleotide reductase

Question 27

Reduction of ribonucleotides to deoxyribonucleotides: Glutaredoxin transfers electrons from ??? to ribonucleotide reductase

Answer 27

glutathione (GSH)

Question 28

Reduction of Ribonucleotides to deoxyribonucleotides: Thioredoxin transfers pair of H+ to ??? required to form dNDP

Answer 28

ribonucleotide reductase

Question 29

ribonucleotide reductase is regulated by the binding of ??? also Deoxynucleoside Triphosphates

Answer 29

effector molecules

Question 30

Regulation of Ribonucleotide Reductase: dATP, dGTP, dTTP, dCTP inhibited by Deoxynucleoside Triphosphate --> dATP at primary or secondary regulation sites?

Answer 30

primary

Question 31

TRUE or FALSE: regulation at primary sites helps regulate overall production

Answer 31

TRUE

Question 32

dTTP is an inhibitor of dUDP and dCDP as well as an activator of dGDP for the regulation of ??? at substrate specific specific sites

Answer 32

ribonucleotide reductase

Question 33

dGTP is an inhibitor of dUDP and dCDP and dGDP as well as an activator of dADP for the regulation of ??? at substrate specific sites

Answer 33

ribonucleotide reductase

Question 34

dTMP (Thymidylate) is derived from dCDP and dUMP. ??? catalyses the conversion of dUMP to dTMP

Answer 34

Thymidylate synthase

Question 35

TRUE or FALSE: Folic acid deficiency results in excess incorporation of uracil into DNA leading to DNA damage causing neural tube defects

Answer 35

true