Lecture 14 - Lecture 14 Regulation of Gene Expression in...

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Lecture 14 Regulation of Gene Expression in Eukaryotes
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Overview of transcriptional regulation Eukaryotic DNA packaged into nucleosomes – regulatory proteins participate in exposing sequences for transcription
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Some differences in bacterial and eukaryotic transcriptional regulation bacteria eukaryotes All genes are transcribed by the same RNA polymerase Three RNA polymerases transcribe distinct subsets of genes Little or no processing of primary transcripts Extensive cotranscriptional processing; modification of 5’ and 3’ ends and intron splicing Relatively simple polymerase with a few associated factors RNA polymerase II is a large, complex collective – coordinates processing activities of associated proteins. Gene regulation in eukaryotes must: ensure that expression of most genes is off at any given time while specific subsets are activated generate the myriad patterns of gene expression that define cell types and developmental stages
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Promoter proximal elements: complexity of eukaryotic promoters CAT box? Just kidding! Single base mutations in core promoter elements reduces transcription TATA box
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Promoter proximal elements are bound by GTFs…a second group of protein components consists of specific transcription factors that bind to cis -acting regulatory sequences in the DNA. These cis elements, which may be situated at a considerable distance(>50kb) from the promoter region (promoter-distal), are called enhancers or upstream activation sequences (UASs) Regulatory proteins must possess one or more of the following functional domains: 1.A domain that recognizes a DNA regulatory sequence (DNA binding site) 2.A domain that interacts with proteins of the transcriptional apparatus (polymerase or associated protein) 3.A domain that interacts with proteins bound to nearby regulatory sequences on DNA such that they can cooperatively regulate transcription 4.A domain that influences chromatin condensation either directly or indirectly 5.A domain that acts as a sensor of physiological conditions within the cell
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The structure of chromatin Before any interaction can occur at promoter proximal or distal sites access must be facilitated via chromatin remodeling cells accomplish the specific exposure of regulatory elements and genes by changing the position of the nucleosome…
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Chromatin remodeling exposes regulatory sequences histone octamer regulatory element Changes in nucleosome density and position is an integral part of eukaryotic transcriptional control…
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Histone tails protrude from the nucleosome…seven of eight histone monomers are shown, modifications are show on one tail, but all may be similarly modified. There are at least 150
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This note was uploaded on 11/11/2009 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas at Austin.

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Lecture 14 - Lecture 14 Regulation of Gene Expression in...

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