Exam 3 Nucleotide Metabolism (RNA) Flashcards
2’ carbon on the 5 membrane ring sugar refers to
ribose (OH) or deoxyribose (H)
all nucleoSide X-phosphates are
nucleoTides
the precursor for all nucleotides
PRPP
-etase signifies
require energy in the form of ATP usu
-tase signifies
does not use energy
what reactants used to make PRPP
- ribose-5-phosphate
2. pyrophosphate from ATP required for the synthetase
the pyrophosphate from ATP attaches where on ribose-5-phosphate
1’ carbon of ribose-5-phosphate
de novo synthesis of pyrimidines is a _ pathway
unidirectional (linear); takes carbamoyl phosphate and PRPP to make UMP then UDP then UTP and then CTP
de novo synthesis of pyrimidines form nitrogenous base _ of PRPP
independent of PRPP; slaps the base on PRPP
the precursors to make pyrimidines
-NH3 from Gln
-Asp
HCO3-
allosteric regulation of pyrimidines: pyr inhibits
C
allosteric regulation of pyrimidines: pur activates
A/G
what is CAD
eukaryotic protein; a complex that uses of 3 enzymes and occurs in the cytosol for pyrimidines
the C in CAD has a channel where what place
CPSII; is a synthetase that modifies HCO3- and the NH3- from Gln as moves down the channel to make carbomyl phosphate
activators of CPSII
PRPP and ATP
inhibitors of CPSII
UTP
A in CAD has 2 allosteric sites which are
ATcase adds Asp to carbamyol phosphate
- ATP activates (excess purines into pyrmidines)
- CTP inhibits ( endput of pyrmidine)
D in CAD (dihydroorotase)
closes the 6 member ring; uses H2O to make pyrimidines
DHODH is located where
mitochondria
FMN is a source of e-s not from
carbohydrates
what does UMP synthetase do
adds orotate (precursor from CAD) adds it to PRPP at the 1’ carbon in ribose backbone then removes carboxyl from Asp to make UMP
our energy used for UMP synthetase
PRPP
what conformation is uracil in after UMP synthetase
SYN
megalobalstic anemia occurs when
cells fail to divide so multi nucleated; b9 or b12 deficiency
hereditary orotic aciduria symptoms include
excess precursor orotate excreted in the urine
why in cases of hereditary orotic aciduria, fails at responding to B9/B12?
it has deficiency of UMP synthetase (no de novo synthesis)
kinases in prymidines used is for
transforming UMP into UTP
_ is the only nucleotide to be synthesized directly as a triphosphate
CTP
CTP synthetase has 2 allosteric regulators:
- GTP activates (base pairing rxns ie CTP uses GTP and UTP uses ATP)
- CTP inhibits both synthetases C and A
purines form nitrogenous base _ PRPP
on PRPP
purines is _ pathway
branched pathway; takes aas and PRPP to make IMP and branch to GMP or AMP
purine regulation via
feedback inhibition by purines
precursors for purines
same 3 in pyrimidines plus Gly and N10-formyl-THF
de novo synthesis of purines happens where
cyoplasm
precursors use what sources of energy
ATP or GTP
how do IMP formation occur
activation/phosphorylation-replacement
making IMP: rxns 1-3 form:
the 5 membered ring
making IMP: rxns 4-10 form:
the 6 membered ring; forming hypoxanthine
in vertebrates, purines are made in the
purinosome (complex)
purinosome: _ enzymes perform 10 reactions
6
_ facilitates flow in purinosome
proximity
kinases in purines are used for:
making diphosphate and triphosphate
precursor IMP to make AMP uses what for energy and is inhibited by
GTP; inhibited by AMP
precursor IMP to make GMP uses what for energy and is inhibited by
ATP; inhibited by GMP
