overview of transcription process of transcription
TRANSCRIPT
Transcription
• Overview of transcription• Process of transcription• Initiation • Elongation • Termination• Eukaryotic transcription
Overview of transcription
• Define transcription • Difference in RNA
and DNA • location in prokaryotic
and eukaryotic cells • What is a gene?
Process of transcription
• What is a gene? • Orientation of genes
Process of transcription
• sense strand (genetic code) • Anti-sense strand (template)
Initiation
• Promoters
• consensus sequence
• strength of the promoter
• -10 Pribnow Box
RNA Initiation
Initiation
• Role of RNA polymerase (open DNA helix) • sigma factor in initiation• Has proofreading ability
Elongation
• 5' to 3' growth of strand
• phosphodiester bonds • chain growth like in
DNA • only core enzyme of
RNA polymerase needed
• 30-50 nucleotides/sec
TerminationRho-factor
Termination: Rho independent
Eukaryotic transcription
• Location • Three RNA
polymerases • Goldberg-Hogness
box (TATA)• CAAT box • Processing of mRNA
in Eukaryotes
Eukaryotic transcriptionPromoter sites in Eukaryotes RNA polymerase
mRNA Processing
• 5' Cap • Poly A Tail; Poly A
polymerase • Exons and introns• Splicing of mRNA,
spliceosome• transport out of the
nucleus
5' Cap Poly A Tail; Poly A polymerase
Splicing of mRNA
• Autocatalytic RNAs: Self-Excision
• Group I introns(rRNA)
• Group II introns from pre-mRNA and pre-tRNA in mito/chloroplasts
• Guanosine cofactor
Splicing of mRNA• Spliceosome: snRNA’s
(100-200 nucleotides)• Removal introns in pre-
mRNA• snRNPs =
ribonucleoproteins• Rich in uridines• U1 complementary to the
5’ donor region in intron