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21 Cards in this Set
- Front
- Back
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What is the rate-limiting enzyme in PURINE synthesis
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glutamine PRPP-amidotransferase
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What is the rate-limiting enzyme in PYRIMIDINE synthesis?
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CPS II
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What are the sources of CARBON used in PURINE synthesis?
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CO2, glycine, THF
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What are the sources of NITROGEN used in PURINE synthesis?
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glutamine, aspartate
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What are the sources of CARBON used in PYRIMIDINE synthesis?
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aspartate, CO2
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What are the sources of NITROGEN used in PYRIMIDINE synthesis?
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glutamine
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Hydroxyurea, MOA
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inh ribonucleotide reductase (UDP --> dUDP) in pyrimidine synth
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Inh DHFR
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Trimethoprim (prokaryotes), MTX (eukaryotes)
(DHFR: DHF --> THF) |
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5-FU, MOA
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inh thymidylate synthase (dUMP --> dTMP) in pyrimidine synthesis
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6-MP, MOA
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inh guanine-PRPP-amidotransferase (rate limiting enz in purine synth, PRPP-->IMP)
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mycophenolate, MOA
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inh IMP dehydrogenase (IMP --> GMP) in purine synth
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Orotic Aciduria
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Orotic acid in urine d/t AR def in UMP synthase (orotic acid --> UMP).
Clin: Orotic aciduria w/o hyperammonemia (seen in OCT). Megaloblastic anemia cannot be corrected with B12 or folate. Failure to thrive. Tx: suppl dietary uridine |
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SCID
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adenosine deaminase def (adenosine--x-> inosine in purine catab & salvage pway).
Clin: severe recurrent infection (Candidiasis, PCP), chronic diarrhea, fail to thrive. No thymic shadow on CXR. |
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Lesch-Nyhan
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def in HGPRT (guanine --x--> GMP and
hypoxanthine --x-> IMP in purine catab & salvage pway). Clin: gout, CNS prob (MR), aggressn, self-mutilation (lip biting), choreoathetosis Tx: allopurinol for gout. No tx for CNS abn |
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Allopurinol, MOA
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inh xanthine oxidase, preventing the production of uric acid in the purine catab & salvage pway.
nb. xanthine oxidase metab Aza & 5-MP, so if used with allopurinol, their toxicity will increase |
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What accounts for the + charge of HISTONES?
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lysine, arginine
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What accounts for the - charge of DNA?
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phosphate grps
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boy with self-mutilating behavior, MR, gout
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Lesch-Nyhan
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orotic acid inn the urine + elevatn in serum ammonia
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Urea Cycle disorder, such as ornithine transcarbamylase def (OCT)
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orotic acid in the urine + NO elevatn in serum ammonia
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Orotic Aciduria d/t def of UMP synthase
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megaloblastic anemia that does not improve with folate and B12
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Orotic Aciduria d/t def of UMP synthase
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