Nucleotide Biosynthesis

Question 1

nucleotide functions

Answer 1

energy for metabolism - atp
enzyme cofactors - nad+
signal transduction - cAMP

Question 2

nucleic acid functions

Answer 2

store genetic info
transmit genetic info
process genetic info
protein synthesis

Question 3

nucleotide

Answer 3

base, sugar, phosphate

Question 4

nucleoside

Answer 4

base and sugar

Question 5

structure of purines

Answer 5

adenine - 2 ring with nh2 group

guanine - 2 ring with carboxy group

Question 6

structure of pyrimidines

Answer 6

cytosine - 1 ring with nh2 group
thymine - 1 ring with carboxy group and methyl group
uracil - 1 ring with carboxy group

Question 7

how is the pentose ring attatched to the nucleobase in nucleotides?

Answer 7

N-glycosidic bond

Question 8

structure and symbols for deoxyadenylate

Answer 8

phosphate, base, and 2 ringed sugar with nh2 group

symbols: A, dA, dAMP
nucleoside: deoxyadenosine

Question 9

structure and symbols for deoxyguanylate

Answer 9

phosphate, base, and 2 ringed sugar with ch2 and carboxy groups

symbols: G, dG, dGMP
nucleoside: deoxyguanosine

Question 10

structure and symbols for deoxythymidylate

Answer 10

phosphate, base, and 1 ringed sugar with 2 carboxys and 1 methyl group

symbols: T, dT, dTMP
nucleoside: deoxythymidine

Question 11

structure and symbols for deoxycytidylate

Answer 11

phosphate, base, and 1 ringed sugar with 1 carboxy and 1 methyl group

symbols: C, dC, dCMP
nucleoside: deoxydytidine

Question 12

main features of de novo nucleotide synthesis

Answer 12

bases synthesized while attached to ribose
gln provides most amino groups
gly is precursor for purines
asp is precursor for pyrimidines
formate

Question 13

significance of PRPP and purines

Answer 13

purine synthesis begins with a reaction of PRPP and glu

Question 14

significance of glycine and purines

Answer 14

purine rings build up with the addition of 3 gly

Question 15

significance of IMP

Answer 15

first intermediate with full purine ring

Question 16

t/f. adenine and guanine are synthesized from IMP

Answer 16

true.

Question 17

how do you get AMP (adenylate) from IMP?

Answer 17

add asp and gtp to IMP and youll get an intermediate (adenylosuccinate). fumarate will leave and you are left with AMP

Question 18

how do you get GMP (guanylate) from IMP?

Answer 18

add water and nad+ to IMP and youll get an intermediate (xanthylate). then add gln and atp (glu and amp+ppi will leave) and you’ll be left with GMP

Question 19

regulation of purine synthesis: glutamine amidotransferase

Answer 19

IMP, AMP, GMP

= feedback inhibition

Question 20

regulation of purine synthesis: imp dh

Answer 20

excess GMP inhibits formation of xanthylate (intermediate) from imp

Question 21

regulation of purine synthesis: gtp and atp

Answer 21

gtp limits imp to amp

atp limits imp to gmp

Question 22

regulation of purine synthesis: PRPP

Answer 22

prpp synthesis is inhibited by adp and gdp

Question 23

features of pyrimidine synthesis

Answer 23

first make the pyrimidine ring, then attach it to the ribose 5 phosphate
use asp with ATCase

Question 24

Ribonucleotide reductase

Answer 24

Can catalyze stable radical reactions in reduction of ribonucleotides to deoxyribonucleotides

Question 25

Two ways to reduce disulfides to activate ribonucleotide reductase

Answer 25

Glutaredoxin (NADPH, glutathione)

Thioredoxin (NADPH, FAD)

Question 26

Why is there an iron center in the ribonucleotide reductase?

Answer 26

To generate the tyr radicle which will then convert the radical to the active site

Question 27

Primary regulation site

Answer 27

If ATP binds, we have energy, so we’ll keep making DNA

If dATP binds, we are low on energy/have plenty of DNA, stop synthesizing

Question 28

Specificity substrate site

Answer 28

dATP, dCTP