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ribose + base
ribose + base + phosphate
amino acids necessary for purine synthesis
gly, asp, glu

also requires CO2 & 2 THF
histone octamer
2 sets H2A, H2B, H3 & H4
mostly lys & arg (+ charge)

2 loops of DNA forms nucleosome bead
enzyme deficiency that leads to excess carbamoyl phosphate, orotic acid & ammonia
ornithine transcarbamoylase deficiency

part of urea cycle
enzyme deficiency that leads to excess orotic acid w/o hyperammonemia
orotic acid phosphoribosyltransferase or orotidine 5'-phosphate decarboxylase deficiency

part of de novo pyrimidine synthesis

auto. recessive
orotic acid + PRPP
de novo pyrimidine synthesis
antineoplastic drug that inhibits ribonucleotide reductase

blocks RNA → DNA
antineoplastic drug that inhibits purine synthesis

blocks AMP & GMP synthesis
antineoplastic drug that inhibits thymidylate synthase

blocks dUMP → dTMP
drug that inhibits dihydrofolate reductase
MTX (antineoplastic), TMP (antibiotic)

blocks DHF → THF
excess ATP & dATP inhibits ribonucleotide reductase preventing DNA synthesis
Adenosine deaminase (ADA) deficiency

part of purine salvage pathway

major cause of SCID
defect in purine salvage pathway that results in excess uric acid
HGPRT deficiency (Lesch-Nyhan syndrome)

X-linked recessive
excess uric acid, gout, retardation, self-mutilation, aggression, choreoathetosis
Lesch-Nyhan syndrome (HGPRT deficiency)

X-linked recessive
HGPRT deficiency
Lesch-Nyhan syndrome

inability to convert guanine & hypoxanthine to GMP & IMP (purine salvage pathway)
conservative missense mutation
new aa is similar in chemical structure to original aa
more than 1 codon can code for same aa
degenerate, redundant genetic code
ADA deficiency

excess ATP & dATP inhibits ribonucleotide reductase (purine salvage pathway)
degenerate genetic code
more than 1 codon can code for same aa
enzyme that relieves DNA supercoils during replication
topoisomerase, gyrase (prokaryotic)
enzyme w/ 3' → 5' exonuclease activity
DNA polymerase III

also synthesizes DNA 5' → 3'
enzyme w/ 5' → 3' exonuclease activity
DNA polymerase I

also excises RNA primer, fills in gap
mutation in nucleotide excision repair
xeroderma pigmentosa

auto. recessive
endonuclease releases DNA w/ damaged bases, repaired by DNA pol III & ligase
nucleotide excision repair
glycosylase removes damaged bases, AP endonuclease cuts DNA, empty sugar is removed, gap is filled & sealed
base excision repair
mismatched nucleotides in unmethylated newly synthesized strand are removed & replaced
mismatch repair
mutation in mismatch repair
hereditary nonpolyposis colorectal cancer (HNPCC)

auto. dominant
brings together 2 ends of DNA fragments regardless of homology
nonhomologous end joining
end of a nucleotide that bears the triphosphate

energy source for RNA & DNA synthesis
stop codons
AT-rich sequence upstream of gene locus
promotor + TATA, CAAT box
makes rRNA
RNA pol I
makes mRNA & snRNP
RNA pol II

inhibited by α-amanitin
α-aminitin MOA
inhibits RNA pol II, causes liver failure
makes tRNA
heterogenous nuclear RNA

initial mRNA transcript before splicing, cap & tail
pt w/ Ab to spliceosomal snRNPs
CCA end of tRNA
3' end

end that binds aa
antibiotic that binds 30S subunit, prevents tRNA attachment
enzyme required for tRNA charging
aminoacyl-tRNA synthetase

1 per aa (therefore, enzyme can work each tRNA that codes for a specific aa)
energy source for tRNA charging
ATP hydrolysis to AMP + PPi
energy source for initiation of protein synthesis
GTP hydrolysis
helps assemble 40S subunit w/ initiator tRNA, released when the complex binds w/ mRNA-60S subunit
antibiotic that inhibits formation of initiation complex

causes mRNA misreading
antibiotic that inhibits 50S peptidyltransferase

inhibits peptide chain elongation
antiobiotic that blocks 50S translocation
macrolide, clindamycin

inhibits peptide chain elongation
post-translational trimming
removal of N- or C-terminal peptides

e.g. zymogens
cells that never go into G0
labile cells

e.g. marrow, skin, gut epithelium, hair folllicles
site of N-linked oligosaccharide addition
molecule that attaches ribosome large subunit to ER
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