Asymmetric transcription Asymmetric transcription:for one structural gene,only one DNA strand serves as template for RNA synthesis. Both DNA strands can serve as template. Nontemplate strand Template strand of gene 1 RNA of gene2 5 GANCCCCAT AUCGGGUA UG DNA 88H88 5 RNA Template strand RNA Nontemplate strand RNA polymerase of gene 1 of gene 2 polymerase Gene 1 Gene2
Asymmetric transcription • Asymmetric transcription: for one structural gene, only one DNA strand serves as template for RNA synthesis. • Both DNA strands can serve as template
Specific sequences on DNA are important for transcription RNA pol protection assay RNA Pol II DNA xaxapodcopook re detected in next step. Digested by nuclease adiolabeled bands on x-ray film ○OOO Uneut DNA- fragment DNA Misning bands indicate Release of binding where RNA polymerase was bound to DNA fragment XOXX It shows RNA pol binding sequence is important for transcription----promoter
Specific sequences on DNA are important for transcription RNA pol protection assay It shows RNA pol binding sequence is important for transcription ---- promoter RNA pol Ⅱ Digested by nuclease Release of binding fragment
Important sequences for transcription: a.Promoter b.Enhancer Regulatory sequence c.terminator d.Structural gene Promoter Structrual gene Terminator Transcrition unit Operon
Important sequences for transcription: a. Promoter b. Enhancer c. terminator d. Structural gene Regulatory sequence Promoter Structrual gene Terminator Transcrition unit Operon
a.Promoter Promoters:locate near the genes they regulate,on the same strand and typically upstream of the antisense strand. Direct the level and accuracy of transcription of a given gene
a. Promoter Promoters：locate near the genes they regulate, on the same strand and typically upstream of the antisense strand. Direct the level and accuracy of transcription of a given gene
Promoter in prokaryote RNA pol binding region Structral gene 5 3 5 Promoter in pro: RNA pol识别和结合 5' 的部位 50 110 3 40 30 20 10 -35:recognition site -35区 Initiation site -10:binding site -10区 TTGACA +1:initiation site AACTGT TATAATPuAT (RNA-pol ATTAPy recognition site) RNA pol binding site TATA box (Pribnow box)
Promoter in prokaryote Initiation site T T G A C A A A C T G T -35 区 RNA pol binding site TATA box (Pribnowbox) T A T A A T Pu A T A T T A Py -10 区 - 1 30 -50 - 10 10 - 40 - 20 5 3 3 5 (RNA-pol recognition site) 5 5 RNApol binding region Structral gene 3 3 Promoter in pro： RNA pol 识别和结合 的部位 -35: recognition site -10: binding site +1: initiation site