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22 terms

Biochem Molecular

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which nucleotide is methylated?
thymine
amino acids necessary for purine synth?
Glycine
Aspartate
Glutamine
nucleotide precursors?
IMP for purines
Orotate + PRPP for pyrimidines
metabolic pathways for carbamoyl phosphate?
de novo pyrimidine synth
urea cycle
cause of orotic aciduria?
(AR) can't convert orotic acid to UMP (pyrimidine synth)
purines?
A, G
pyrimidines?
C, T, U
OTC def vs orotic aciduria?
hyperammonemia in OTC (b/c defective urea cycle), not in orotic aciduria
major cause of SCID?
adenosine deaminase deficiency (purine salvage)
adenosine deaminase def?
excess ATP imbalances nucleotide pool via inhib of ribonucleotide reductase, thus no DNA synth so low lymphocytes
deficiency in Lesch Nyhan?
HGPRT, which is supposed to convert hypoxanthine to IMP, and guanine to GMP (purine salvage)
dx if 'sand' in diaper or 'diamonds' in urine?
excess uric acid (e.g. Lesch-Nyhan)
fx of DNA pol III?
5->3 synth and 3->5 exonuclease proofreading
fx of DNA pol I?
excises RNA primer 5->3 then fills in gap
mutation for xeroderma pigmentosum?
nucleotide excision repair of thymidine dimers
nucleotide excision repair defect of thymidine dimers causes...?
xeroderma pigmentosum
mutation for HNPCC?
mismatch repair
mismatch repair defect best known in what disease?
HNPCC
natural RNA pol II inhibitor?
alpha-amanitin found in death cap mushrooms, ingestion leads to liver failure
what disease includes antibodies to spliceosomal snRNPs?
lupus
universal 3' end of tRNA?
CCA
accuracy of amino acid selection insured by...?
aminoacyl-tRNA synthetase (scrutinizes before and after)