nucleotides and nucleic acids

Question 1

what are the 4 uses of nucleotides?

Answer 1

precursors for nucleic acids (DNA, RNA)
make derivatives for biochemical processes (UDP-glucose)
components of signaling pathways (cAMP)
energy source (ATP, GTP)

Question 2

what are the ribonucleosides?

Answer 2

adenosine
guanosine
cytidine
uridine

Question 3

what are the deoxyribonucleosides?

Answer 3

deoxyadenosine
deoxyguanosine
deoxycytidine
thymidine

Question 4

what are the 2 methods of synthesizing nucleotides?

Answer 4

de novo synthesis

salvage pathway

Question 5

what is the de novo synthesis pathway

Answer 5

start from scratch
purines- start with ribose and add piece by piece
pyrimidines- form base piece by piece and add to ribose

Question 6

what is the salvage pathway?

Answer 6

recycle preformed bases from degradation of old nucleotides

add a ribose unit

Question 7

we form deoxyribonucleotides by reducing a ribonucleotide using what enzyme?

Answer 7

ribonucleotide reductase

Question 8

de novo pathways form?

Answer 8

ribonucleotides

Question 9

what is an activated pentose required for de novo synthesis and salvage of both purines and pyrimidines

Answer 9

5-phosphoribosyl-1-pyrophosphate

Question 10

ribose-5-phosphate ->

Answer 10

PRPP

Question 11

where does purine synthesis happen?

Answer 11

primarily the liver

Question 12

PRPP is derived from?

Answer 12

ribose-5-phosphate

Question 13

what is the process of purine de novo synthesis?

Answer 13

start with PRPP
build the purine base on the ribose
form a purine nucleotide

Question 14

what is the AA needed in the committed step of purine synthesis?

Answer 14

glutamine

Question 15

IMP (inosine monophosphate) is the starting material for both?

Answer 15

AMP

GMP

Question 16

what is the primary location for de novo synthesis of purines and can supply purines to peripheral tissues?

Answer 16

liver

Question 17

non-hepatic has little to do with de novo synthesis and instead relies on?

Answer 17

salvage pathways

Question 18

how does purine salvage pathway happen?

Answer 18

normal cell turnover

degradation/breakdown of nucleotides into bases

Question 19

what enzymes are needed for the purine salvage pathway?

Answer 19

phosphoribosyltransferases

A-PRT
HG-PRT

Question 20

the purine salvage pathway uses more or less ATP?

Answer 20

less ATP; it is a significant source of purines

Question 21

hypoxanthine inhibits the _______ ________ of de novo synthesis

Answer 21

committed step

Question 22

purine salvage pathway recovers bases from breaking down ______ and _______ or turnover of _______ from diet

Answer 22

DNA, RNA, nucleotides

Question 23

purine synthesis pathway attaches base to PRPP and produces a __________?

Answer 23

nucleotide monophosphate

Question 24

what happens if there was an enzyme deficiency in the purine salvage pathway?

Answer 24

brain would be overwhelmed with de novo synthesis and couldn’t utilize the pathway

Lesch-Nyhan syndrome

Question 25

further breakdown of purines requires

Answer 25

xanthine oxidase

Question 26

what is the enzyme that is oxidized to produce uric acid?

Answer 26

xanthine oxidase

Question 27

free bases converted into common bases =

Answer 27

xanthine

Question 28

what is the final metabolic product of purine catabolism?

Answer 28

uric acid

Question 29

what inhibits xanthine oxidase?

Answer 29

allopurinal

Question 30

which synthetic drug is an inhibitor of purine synthesis?

Answer 30

methotrexate- also inhibits tetrahydrofolate cancer, rheumatoid arthritis and psoriasis treatment

Question 31

what is the location of pyrimidine de novo synthesis?

Answer 31

spleen thymus GI tract testes

Question 32

what is the regulatory step of pyrimidine synthesis?

Answer 32

carbamoyl phosphate

Question 33

what inhibits and stimulates carbamoyl phosphate

Answer 33

inhibited by UTP | stimulated by PRPP

Question 34

what is the enzyme needed in the regulatory step of pyrimidine synthesis?

Answer 34

carbamoyl phosphate synthetase

Question 35

what forms the ring in pyrimidine synthesis?

Answer 35

CAD

Question 36

what does CAD stand for?

Answer 36

Carbamoyl phosphate synthetase Aspartate transcarbamyolase Dihydrorotase

Question 37

what is CTP synthesized from?

Answer 37

uracil - UMP first is phosphorylated to UDP, then UTP

Question 38

what enzyme is needed for amination of UTP to form CTP?

Answer 38

CTP synthetase

Question 39

what 2 amino acids are needed for the formation of CTP from UTP?

Answer 39

glutamate | glutamine

Question 40

TMP is unique to DNA and needs which enzyme?

Answer 40

ribonucleotide reductase

Question 41

what enzyme catalyses the formation of deoxyribonucleotides?

Answer 41

ribonucleotide reductase

Question 42

what enzyme is needed for thymidine synthesis?

Answer 42

thymidylate synthase- NADPH is also required

Question 43

what does the pyrimidine salvage pathway break down?

Answer 43

not as significant as purine; nitrogen transferred to form AAs (glutamate) what is left can be converted into FA synthesis or krebs intermediates

Question 44

what enzymes are required for pyrimidine salvage pathway?

Answer 44

nucleoside phosphorylase | nucleoside kinase

Question 45

the pyrimidine salvage pathway is the primary pathway for?

Answer 45

uracil and thymine

Question 46

what 3 amino acids donate nitrogen?

Answer 46

aspartate glutamate glutamine

Question 47

what are the 3 donors of carbon?

Answer 47

bicarbonate CO2 THF