Nucleotide Biosynthesis Flashcards Preview

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Flashcards in Nucleotide Biosynthesis Deck (28):
1

nucleotide functions

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

2

nucleic acid functions

store genetic info
transmit genetic info
process genetic info
protein synthesis

3

nucleotide

base, sugar, phosphate

4

nucleoside

base and sugar

5

structure of purines

adenine - 2 ring with nh2 group
guanine - 2 ring with carboxy group

6

structure of pyrimidines

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

7

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

N-glycosidic bond

8

structure and symbols for deoxyadenylate

phosphate, base, and 2 ringed sugar with nh2 group
symbols: A, dA, dAMP
nucleoside: deoxyadenosine

9

structure and symbols for deoxyguanylate

phosphate, base, and 2 ringed sugar with ch2 and carboxy groups
symbols: G, dG, dGMP
nucleoside: deoxyguanosine

10

structure and symbols for deoxythymidylate

phosphate, base, and 1 ringed sugar with 2 carboxys and 1 methyl group
symbols: T, dT, dTMP
nucleoside: deoxythymidine

11

structure and symbols for deoxycytidylate

phosphate, base, and 1 ringed sugar with 1 carboxy and 1 methyl group
symbols: C, dC, dCMP
nucleoside: deoxydytidine

12

main features of de novo nucleotide synthesis

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

13

significance of PRPP and purines

purine synthesis begins with a reaction of PRPP and glu

14

significance of glycine and purines

purine rings build up with the addition of 3 gly

15

significance of IMP

first intermediate with full purine ring

16

t/f. adenine and guanine are synthesized from IMP

true.

17

how do you get AMP (adenylate) from IMP?

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

18

how do you get GMP (guanylate) from IMP?

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

19

regulation of purine synthesis: glutamine amidotransferase

IMP, AMP, GMP
= feedback inhibition

20

regulation of purine synthesis: imp dh

excess GMP inhibits formation of xanthylate (intermediate) from imp

21

regulation of purine synthesis: gtp and atp

gtp limits imp to amp
atp limits imp to gmp

22

regulation of purine synthesis: PRPP

prpp synthesis is inhibited by adp and gdp

23

features of pyrimidine synthesis

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

24

Ribonucleotide reductase

Can catalyze stable radical reactions in reduction of ribonucleotides to deoxyribonucleotides

25

Two ways to reduce disulfides to activate ribonucleotide reductase

Glutaredoxin (NADPH, glutathione)
Thioredoxin (NADPH, FAD)

26

Why is there an iron center in the ribonucleotide reductase?

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

27

Primary regulation site

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

28

Specificity substrate site

dATP, dCTP