Transcription and disorders Flashcards
(19 cards)
RNAP
uses DNA as a template, synthesizing in the 5’-3’ direction while reading in the 3’-5’ direction. Does not require a primer, and cannot proofread, so error rate is high.
major points of prok translation
- 1 type of RNAP for all RNA
- uses sigma factor as TF
- promoter escapes via DNA scrunching
- Termination is Rho-dependent or Rho-independent
prok promoter regions
Pribnow box 10 bp, 35 bp.
euk promoter regions
TATA box, many others - each specific for its assembly role.
euk initiation
**each step of assembly has its own TF
**helicase unwinds DNA
**CTD (carboxy terminal domain) is phosphorylated, thus ACTIVE, allows promoter escape
euk elongation
uses elongation factors to bind RNAP
euk termination
EFs dissociate, CTD dephosphorylated thus inactive, termination signal read and poly A tail added
prok elongation
- promoter escapes via DNA scrunching
- sigma factor recycled
prok termination
rho dependent or rho independent
inhibitor of prok RNAP
Rifampin, used to treat leprosy and TB, blocks the beta subunit of RNAP thus blocking active site
inhibitor of euk RNAP
alpha-amanitin, produced by mushroom, toxin binds to largest subunit of RNAP
rho-dependent termination
rho helicase uses ATP to snip off the new mRNA
rho-independent termination
palindromic G/C rich hairpin forms which stops RNAP and U rich tail is pulled out of RNAP
post-translational mods of pre-RNA in euks only
- 7 methylguanosine cap at 5’ end
- splicing thru spliceosome
- poly A tail at 3’ end (gets shortened thru lifespan)
- export from nucleus
viral cap snatching
virus replicates host cap on mRNA for more efficient translation by ribosomes, as well as protection from proteases and foreign detection
spliceosome
consists of snRNPs made up of snRNAs that are rich in uridine (U1,2,4,5,6).
The snRNPs excise the introns from mRNA and ligase seals the exons together with exon junction complex.
retinitis pigmentosa
degenerative disease that causes progressive loss of night and peripheral vision due to rod cell death; rod cells die because of build up of unprocessed/misprocessed Rhodopsin pigment which is controlled by 4 snRNP proteins which are implicated in the disease
systemic lupus erythematous
patient makes antibodies for snRNPs which are ubiquitously expressed, thus has widespread inflammation, butterfly rash, muscle aches, arthritis.
ANA screen tests for antinuclear anbodies.
polyadenylation disorders
alternative polyadenylation has uses in neurons and cell diff but causes the length of the 3’ UTR to change, thus possibly changing the binding sites of microRNA
assc with many diseases including type 1+2 DM, fragile X associated OI, cancers
