RNA TRANSCRIPTION Flashcards
What is the most abundant RNA?
Rrna (80%)
What is the function of micro RNA..?
Always silencing of gene
Post transcription
What type of polymerase is used in transcription ?
DNA dependant Rna Polymerase
Which strand is usually read during transcription ?
Non coding / template strand
What site in transcription decides the direction of Transcription ?
TSS
What is the role of Sigma factor in transcription ?
Guides the polymerase to -10 or -35 (Tata box or pi now box) to initiate transcript
Does rna polymerase use NTP OR DNTP in elongation in transcription ?
NTP
What type of bond is formed between growing strand and NTP in transcription ?
Phosphodiaster bond
Between 3’OH of growing and 1st phosphate of NTP
What are the two types of termination in RNA transcription?
Rho depend (use atp to pull Mrna)
Rho indep ( forms GC RICH PALINDROME SEQUENCE)
What are the three drugs used to stop transcription ?
Rifampicin ( prok) (to treat TB)
Actinomycin ( prok and euk)
Alpha amantin ( euk) (MUSHROOMS)
What is the initiation factor in eukaryotic transcription ?
TBP OR TF2D
What are the 3 rna polymerases and what RNA does it produce ?
1 - 28s Rrna
2- mRNA,miRNA,snRNA
3 - TRNA, 5srRna
Explain the process of Transcription elongation in eukaryotes?
Pre initating complex CTD DOMAIN is the domain of RNA polymerase 2
CTD tail phosphorylation = turns on
RNA polymerase 2 synthesises Mrna
What are the three types of post transcription processing ?
Capping at 5’ by 7 methyl guanosin cap
POLY A tail add in 3’
Splicing of introns by spliceosomes
What is the mechanism of Splicing of introns ?
Introns consists of 3 regions
DONOR at 5’ (GU)
ACCEPTOR at 3’ (AG)
BRANCH POINT at the internal site within introns
snRNPs binds U1 to donar and acceptor
Binds U2 and U6 in branch point
Cleaves of by forming lariat structure btwn donar and branch point
Removes the lariat structure
