Lecture 21 done

Lecture 21 done - 1. How does competitive DNA binding...

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1. How does “competitive DNA binding” contributes to transcription repression at certain genes? This occurs when the binding site for the repressor and activator overlap, so when a repressor is bound to DNA, an activator is partially blocked from its binding site and therefore cannot bind to the given strand of DNA. 2. What is called “quenching” in transcription repression? This occurs when the binding site of the repressor and the binding site of the activator are within close proximity of each other. The activation surface of the activator is bound by the repressor, causing the two to bend, or “quench” towards each other. This is also called “masking the activation surface” 3. How can sequence-specific repressors inhibit transcription by contacting components of the general/basal transcription machinery? This is a direct interaction with the general transcription factors. Once the repressor is bound it its binding site, it binds to the transcription machinery (TFIID, TBP, TAFs, etc) located on the TATA box. The DNA is looped back around so that the repressor can reach the machinery. This prevents activators from contacting general transcription factors, and also prevents assembly of other GTFs and Pol II into a complete pre-initiation complex (PIC) 4. How can heterodimerization of a sequence-specific activator (e.g. MyoD) with a dominant negative partner protein (e.g. Id) inhibit the function of the activator? **SEE BOOK**
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This note was uploaded on 06/08/2009 for the course BCH 120 taught by Professor Luben,norman,henry during the Spring '09 term at UC Riverside.

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Lecture 21 done - 1. How does competitive DNA binding...

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