Molecular Flashcards
2 a.a. that histones are rich in
Lysine & arginine
neg charged DNA that loops around positively charged histone octamer consisting of [H2A, H2B, H3, H4] x 2
nucleosome
what histone binds to the nucleosome and to linker DNA to stabilize chromatin fiber
H1
3 necessary a.a. for purine synthesis
glycine, aspartate, glutamine
enzyme that converts ribonucleotides to deoxyribonucleotides in pyrimidine synthesis
ribonucleotide reductase
carbamoyl phosphate is involved in which 2 metabolic pathways…
de novo pyrimidine synthesis
urea cycle
drug that inhibits dihydroorotate dehydrogenase causing a build up of carbamoyl phosphate and low orotic acid (pyrimidine synth)
Leflunomide
2 drugs that inhibit IMP dehydrogenase in purine synthesis
Mycophenolate
Ribavirin
drug that inhibits ribonucleotide reductase
hydroxyurea
2 drugs that inhibit de novo purine synthesis
6-mercaptopurine & it’s pro drug azathioprine
drug that inhibits thymidylate synthase thereby decreasing dTMP
5-fluorouracil
3 drugs that inhibit dihydrofolate reductase (decr dTMP) in humans, bacteria, protozoa
humans- methotrexate
bacteria- TMP
protozoa- pyrimethamine
auto recessive deficiency of adenosine deaminase: excess ATP & dATP causes feedback inhib of ribonucleotide reductase - prevents DNA synth - lowers lymphocyte count
SCID
defective purine salvage d/t absent HGPRT which converts hypoxanthine to IMP and guanine to GMP to recycle purines - results in excess uric acid & de novo purine synth
X linked recessive
causes intellect disability, self mutilation, aggression, hyperuricemia, gout, dystonia
Lesch Nyhan syndrome
AUG
methionine start codon in eukaryotes
codes for N-formylmethionine in prokaryotes - stimulates neutrophil chemotaxis
UGG
tryptophan
drug that inhibits prokaryotic enzyme topoisomerase II & IV
fluoroquinolones
prokaryotic DNApol with 5’ to 3’ synth and 3’ to 5’ exonuclease proofreading
DNA polymerase III
prokaryotic DNApol that degrades RNA primer & replaces it with DNA
same functions as DNApol III but also excises RNA primer with 5’ to 3’ exonuclease
DNA polymerase I
catalyzes formation of phosphodiester bond within a strand of dsDNA (joints Okazaki fragments)
DNA ligase
RNA-dependent DNA pol that adds DNA to 3’ ends of chrom to avoid loss of genetic material with every duplication (euk only)
telomerase
DNA mutation with nt substitution causing changed a.a.
missense point mutation
DNA mutation with nt substitution causing early stop codon
nonsense point mutation
low glucose - incr adenylyl cyclase activity - incr generation of cAMP from ATP - activates catabolite activator protein - transcription increases
MOA for lac operon in E. coli with glucose absent to do lactose metabolism
high lactose - unbinds repressor protein from repressor/operator site - transcription increases
MOA for lac operon in E. coli with high lactose to do lactose metabolism
defective nt excision repair in G1 preventing repair of pyrimidine dimers from UV light exposure
xeroderma pigmentosum
defective mismatch repair in G2 phase of cell cycyle
hereditary nonpolyposis colorectal cancer
mutated non homologous end joining to bring together 2 ends of DNA fragments to repair ds breaks
ataxia telangiectasia
Fanconi anemia
UGA, UAA, UAG
mRNA stop codons
‘U Go Away’
‘U Are Away’
‘U Are Gone’
RNA polymerase I
makes rRNA in eukaryotes
RNA polymerase II
makes mRNA in eukaryotes
opens DNA at promoter site
RNA polymerase III
makes tRNA in eukaryotes
toxin found in Amanita phalloides (death cap mushrooms) that inhib RNApol II - causes severe hepatotoxicity
alpha amanitin
drug that inhibits RNApol in prok
Rifampin
drug that inhib RNApol in both prok & euk
Actinomycin D
prokaryotic RNA polymerase
1 RNA polymerase (multisubunit complex) makes all 3 kinds of RNA
processes that occur in the nucleus to hnRNA to modify it into mRNA
capping of 5’ end (add 7-methylguanosine cap)
polyadenylation of 3’ end (AAUAAA)
splicing out introns
where does translation occur in the cell?
cytosol
function of snRNPs in spliceosome forming a lariat
splicing of pre-mRNA to remove introns
Ab to spliceosomal snRNPs
anti-Smith Ab highly specific for SLE
anti-U1 RNP Ab
mixed connective tissue disease
3 base sequence at 3’ end of all tRNA’s to which the a.a. binds
CCA
T arm of tRNA
thymine, pseudouracil, cytosine
necessary for tRNA-ribosome binding
D arm of tRNA
dihydrouracil residues needed for tRNA recognition by correct aminoacyl-tRNA synthetase
aminoacyl-tRNA synthetase
1 per a.a.
uses ATP to check a.a. before & after binding tRNA (if incorrect, it hydrolyzes the bond)
GTP hydrolysis with initiation factors to assemble 40S with initiator tRNA
protein synthesis initiation
eukaryotic ribosomes
40S + 60S = 80S
prokaryotic ribosomes
30S + 50S = 70S
protein synthesis elongation A site
aminoacyl-tRNA binds here (except for methionine)
protein synthesis elongation P site
accommodates growing peptide - peptide bond formation
protein synthesis elongation E site
holds empty tRNA as it exits (translocation)
removal of N- or C-terminal propeptides from zymogen to make mature protein
trimming posttranslational modification
intracell protein that facilitates protein folding
chaperone proteins
