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Unformatted text preview: Lab 11 – Repression Assays 11-1 Lab 11 X-gal Filter Lift Assay: testing the Hst:Sir mutants for transcriptional repression. In this experiment, each person will determine if their Hst:Sir chimera mutants are able to repress transcription of a LacZ reporter gene that is under control of a Hst1-repressed promoter. In wild type HST1 strains the reporter is transcriptionally repressed and so the yeast strains are unable to express the β-galactosidase enzyme that is coded by the lacZ gene. These cells will be white on the X-gal indicator plates. In an hst1 mutant strain the lacZ gene is no longer repressed and so these cells will be blue on X-gal plates. In this lab you will use your streak out plates to determine if any of your mutants cause derepression of a LacZ reporter gene. The X-gal filter assays are a qualitative method used to determine if the Hst:Sir chimera mutants are able to repress transcription of the lacZ reporter. In this assay, yeast that grow on a petri plate are transferred to a piece of filter paper and frozen in...
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- Spring '10
- Transcription, X-gal, Sir chimera mutants