上帝充通大学 Shanghai Jiao Tong University Overview of Transcription Only one of the two strands of DNA are transcribed by RNA polymerase for any gene Genes are present on both strands of DNA,but at different locations RNA polymerase has five different subunits RNA polymerase recognizes DNA sites called promoters No.6 Chen Feng.Shanghai Jiao Tong University
No. 6 Chen Feng, Shanghai Jiao Tong University Only one of the two strands of DNA are transcribed by RNA polymerase for any gene Genes are present on both strands of DNA, but at different locations RNA polymerase has five different subunits RNA polymerase recognizes DNA sites called promoters Overview of Transcription
上帝充通大学 Shanghai Jiao Tong University Overview of Transcription Promoters:site of initiation of transcription Recognized by sigma factor of RNA polymerase Transcription stops at specific sites called transcription terminators Unlike DNA replication,transcription involves smaller units of DNA Often as small as a single gene Allows cell to transcribe different genes at different rates No.7 Chen Feng.Shanghai Jiao Tong University
No. 7 Chen Feng, Shanghai Jiao Tong University Promoters: site of initiation of transcription • Recognized by sigma factor of RNA polymerase Transcription stops at specific sites called transcription terminators Unlike DNA replication, transcription involves smaller units of DNA • Often as small as a single gene • Allows cell to transcribe different genes at different rates Overview of Transcription
Steps in RNA synthesis 1:Initiation Initiate Terminate Promoter The initiation and termination sites are specific nucleotide sequences on region the DNA.初始化位点与终止点为特定序列 5' 3 1 Gene 5 RNA polymerase (core enzyme) Sigma aids in recognition of Sigma factor promoter and initiation site 5 3 3 5 The sigma factor allows RNA polymerase to recognize the initiation site(the promoter'）.启动子的识别
Steps in RNA synthesis 1: Initiation The initiation and termination sites are specific nucleotide sequences on the DNA.初始化位点与终止点为特定序列 The sigma factor allows RNA polymerase to recognize the initiation site (the promoter). 启动子的识别
Steps in RNA synthesis 2:elongation The sigma factor is released Sigma during elongation. 5 3 3 5' Transcription begins; Elongation:RNA polymerase moves down the DNA chain,causing temporary sigma released opening of the double helix..a延长阶段 5 3 3 5 RNA chain 5 growth
Elongation: RNA polymerase moves down the DNA chain, causing temporary opening of the double helix.延长阶段 The sigma factor is released during elongation. Steps in RNA synthesis 2: elongation
Steps in RNA synthesis 3:termination 5 3 3 5 Termination site reached:chain 5 growth stops When a termination site is reached, and the mRNA and polymerase are 5 released. 3 3 5 Release of polymerase 3 and RNA 5 FLASH 2
When a termination site is reached, and the mRNA and polymerase are released. Steps in RNA synthesis 3: termination FLASH 2