GeneRegulation160-page2 - • Another type of regulatory...

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Gene Regulation - 2 Regulating Gene Expression in Prokaryotic Transcription The early work on gene regulation was done with prokaryotes. It is easier to study activity in prokaryotes because they are less genetically complex, and absent a nucleus, the DNA is accessible to all components of the cell. Much of the research in gene regulation has been accomplished with Escherichia coli , the common intestinal bacterium. Moreover, gene expression in prokaryotes is organized into a discreet "package" the operon. Before we go too far, however, we need our vocabulary. Recall that the typical gene codes for a polypeptide that is used to help the cell function in some way, or codes for some structural protein. A gene that codes for such proteins is a structural gene. Other Regulatory genes control how much of and when polypeptide gets formed. Some regulatory genes code for small polypeptides that control how other genes get expressed. These polypeptides are called transcription factors. There are a number of different types of transcription factors.
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Unformatted text preview: • Another type of regulatory gene is a piece of DNA that a transcription factor binds to. These regulatory sites of DNA do not actually code for any protein. The Operon of the Prokaryotic Cell An active gene (or group of genes) includes the DNA that will be transcribed, the structural gene, along with a promoter and operator. This complex is known as the operon and was described in 1961 by Francois Jacob and Jacques Monod. An operon has four parts: promoter, operator and structural gene plus a regulatory gene that activates or represses the operon. Operon • Specific Regulatory Gene Controls how other genes are expressed • Promoter Recognized by RNA polymerase as the place to start transcription • Operator Controls RNA polymerase's access to the promoter, and is usually located within the promoter or between the promoter and the transcribable gene (or set of genes) • Structural (Transcribable) Gene Codes for the needed protein...
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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