MCB 2007 October 17th and 19th Lecture Notes

MCB 2007 October 17th and 19th Lecture Notes - October 17th...

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October 17 th and 19 th Lecture Notes: (Ch. 8 – Control of Gene Expression) An Overview of Gene Expression o the different cell types of a multi-cellular organism all contain the same DNA how does differentiation occur? o different cell types produce different sets of proteins different genes are expressed in differentiated cells o a cell can change the expression of its genes in response to external signals extracellular signaling molecules can affect gene transcription… affects what genes a cell expresses o gene expression can be regulated at many of the steps in the pathway from DNA to RNA to proteins o transcription is the major control point for gene expression in both prokaryotes and eukaryotes How transcriptional switches work o transcription is controlled by proteins binding to regulatory DNA sequences (“gene regulatory proteins”) proteins contain a variety of DNA-binding motifs common feature = a homeodomain of three alpha helices, asparigine, arginine, and serine residues are responsible for DNA interactions Zn fingers wrap around the major groove of a DNA region leucine finger motifs grip the DNA helix like a clothespin o proteins are able to interact with the DNA because the surface of the protein fits tightly with the features of the double-helix at that specific region (are very specific and very tight)
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o regulatory sequences are located upstream from the promoter and can be quite distant. They can have both positive and negative effects on gene
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This note was uploaded on 05/11/2008 for the course BI 304 taught by Professor Oconnorandburgess during the Spring '08 term at BC.

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MCB 2007 October 17th and 19th Lecture Notes - October 17th...

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