450 likes | 572 Views
s 70. Ways to Regulate Transcription. Alternate sigma factor usage : controls selective transcription of entire sets of genes. vegetative (principal s). +1. צמיחה. (16-19 bp). (5-9 bp). A. TTGACA. TATAAT. heat shock. +1. s 32. (13-15 bp).
E N D
s70 Ways to Regulate Transcription Alternate sigma factor usage: controls selective transcription of entire sets of genes vegetative (principal s) +1 צמיחה (16-19 bp) (5-9 bp) A TTGACA TATAAT heat shock +1 s32 (13-15 bp) (5-9 bp) A CNCTTGA CCCATNT +1 nitrogen starvation s60 (6 bp) (5-9 bp) TTGCA A CTGGNA התרגיל ביום חמישי זה – 19.6.2008!
Pre-mRNA * microRNAs (miRNA) RNA molecules of about 21–23 nucleotides in length, which regulate gene expression. are processed from primary transcripts known as pri-miRNA.
5’UTR 3’UTR
מיקום +1 רמה נמוכה (בזלית) יעילות ותדירות אינטרונים E S RE
אין אחידות במיקום וברצפי הבקרה בין גנים שונים.
שלבי הטרנסקריפציה • Initiation • Elongation • Termination
קומפלקס פרה-איניציציה יציבות ותדירות יצירת קומפלקס זה קובעת את כמות וקצב סינטזת ה-RNA
אופן אקטיבציה של טרנסקריפציה בתאים אוקריוטים
Bacterial transcription Closed complex: holoenzyme+promoter Open complex (DNA melting, not need ATP) Abortive transcripton Productive initiation Transcribe past +9 Sigma dissociates Elongation Eukaryotic transcription Preinitiation complex (PIC) assembly PIC activation (DNA melting, needs ATP) Abortive transcription Productive initiation CTD phosphorylated Promoter clearance Elongation Stages in Initiation of Transcription
Elongation NTPs
TERMINATION • RNA polymerase meets the terminator • Terminator sequence: AAUAAA • RNA polymerase releases from DNA • Prokaryotes-releases at termination signal • Eukaryotes-releases 10-35 base pairs after termination signal
Gene expression Gene expression
Basics of cell biology:development Fertilized egg
Basics of cell biology:development Cells differentiation is due to different gene Switches going on and off These cells are different because they express a subset of their 24,000 genes
Promoter Gene To specify a new cell: place it in the right environment or
Promoter Gene EGF Hedgehog Wnt Retinoic acid FGF HGF To specify a new cell: place it in the right environment or Substitute drugs/proteins for environment Mophogens
Chromosome localization in interphase In interphase, chromosomes appear to be localized to a sub-region of the nucleus.