Exam 3 Nucleotide Metabolism (RNA)

Question 1

2’ carbon on the 5 membrane ring sugar refers to

Answer 1

ribose (OH) or deoxyribose (H)

Question 2

all nucleoSide X-phosphates are

Answer 2

nucleoTides

Question 3

the precursor for all nucleotides

Answer 3

PRPP

Question 4

-etase signifies

Answer 4

require energy in the form of ATP usu

Question 5

-tase signifies

Answer 5

does not use energy

Question 6

what reactants used to make PRPP

Answer 6

1. ribose-5-phosphate

2. pyrophosphate from ATP required for the synthetase

Question 7

the pyrophosphate from ATP attaches where on ribose-5-phosphate

Answer 7

1’ carbon of ribose-5-phosphate

Question 8

de novo synthesis of pyrimidines is a _ pathway

Answer 8

unidirectional (linear); takes carbamoyl phosphate and PRPP to make UMP then UDP then UTP and then CTP

Question 9

de novo synthesis of pyrimidines form nitrogenous base _ of PRPP

Answer 9

independent of PRPP; slaps the base on PRPP

Question 10

the precursors to make pyrimidines

Answer 10

-NH3 from Gln
-Asp
HCO3-

Question 11

allosteric regulation of pyrimidines: pyr inhibits

Answer 11

C

Question 12

allosteric regulation of pyrimidines: pur activates

Answer 12

A/G

Question 13

what is CAD

Answer 13

eukaryotic protein; a complex that uses of 3 enzymes and occurs in the cytosol for pyrimidines

Question 14

the C in CAD has a channel where what place

Answer 14

CPSII; is a synthetase that modifies HCO3- and the NH3- from Gln as moves down the channel to make carbomyl phosphate

Question 15

activators of CPSII

Answer 15

PRPP and ATP

Question 16

inhibitors of CPSII

Answer 16

UTP

Question 17

A in CAD has 2 allosteric sites which are

Answer 17

ATcase adds Asp to carbamyol phosphate

1. ATP activates (excess purines into pyrmidines)
2. CTP inhibits ( endput of pyrmidine)

Question 18

D in CAD (dihydroorotase)

Answer 18

closes the 6 member ring; uses H2O to make pyrimidines

Question 19

DHODH is located where

Answer 19

mitochondria

Question 20

FMN is a source of e-s not from

Answer 20

carbohydrates

Question 21

what does UMP synthetase do

Answer 21

adds orotate (precursor from CAD) adds it to PRPP at the 1’ carbon in ribose backbone then removes carboxyl from Asp to make UMP

Question 22

our energy used for UMP synthetase

Answer 22

PRPP

Question 23

what conformation is uracil in after UMP synthetase

Answer 23

SYN

Question 24

megalobalstic anemia occurs when

Answer 24

cells fail to divide so multi nucleated; b9 or b12 deficiency

Question 25

hereditary orotic aciduria symptoms include

Answer 25

excess precursor orotate excreted in the urine

Question 26

why in cases of hereditary orotic aciduria, fails at responding to B9/B12?

Answer 26

it has deficiency of UMP synthetase (no de novo synthesis)

Question 27

kinases in prymidines used is for

Answer 27

transforming UMP into UTP

Question 28

_ is the only nucleotide to be synthesized directly as a triphosphate

Answer 28

CTP

Question 29

CTP synthetase has 2 allosteric regulators:

Answer 29

1. GTP activates (base pairing rxns ie CTP uses GTP and UTP uses ATP)
2. CTP inhibits both synthetases C and A

Question 30

purines form nitrogenous base _ PRPP

Answer 30

on PRPP

Question 31

purines is _ pathway

Answer 31

branched pathway; takes aas and PRPP to make IMP and branch to GMP or AMP

Question 32

purine regulation via

Answer 32

feedback inhibition by purines

Question 33

precursors for purines

Answer 33

same 3 in pyrimidines plus Gly and N10-formyl-THF

Question 34

de novo synthesis of purines happens where

Answer 34

cyoplasm

Question 35

precursors use what sources of energy

Answer 35

ATP or GTP

Question 36

how do IMP formation occur

Answer 36

activation/phosphorylation-replacement

Question 37

making IMP: rxns 1-3 form:

Answer 37

the 5 membered ring

Question 38

making IMP: rxns 4-10 form:

Answer 38

the 6 membered ring; forming hypoxanthine

Question 39

in vertebrates, purines are made in the

Answer 39

purinosome (complex)

Question 40

purinosome: _ enzymes perform 10 reactions

Answer 40

6

Question 41

_ facilitates flow in purinosome

Answer 41

proximity

Question 42

kinases in purines are used for:

Answer 42

making diphosphate and triphosphate

Question 43

precursor IMP to make AMP uses what for energy and is inhibited by

Answer 43

GTP; inhibited by AMP

Question 44

precursor IMP to make GMP uses what for energy and is inhibited by

Answer 44

ATP; inhibited by GMP