MBB 222 Study Guide - Final Guide: Conformational Change, Repressor, Lac Repressor
9 Dec 2016
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The phenotype/characteristic that is displayed due to a particular gene. Regulated gene expression is varying gene expression in response to a molecular signal. Genes that are expressed at a constant level in virtually every cell of a species or organism. Steady, unvarying level of expression of a gene. Positive: when activators bind to dna and enhance the activity of rna polymerase at a promoter. Negative: regulation by means of a repressor protein that blocks transcription (repressors): inducible/induction vs. repressible/repression. Gene products that increase in concentration under particular molecular circumstances are referred to as inducible (inducers counter repression by binding to the repressor and causing it to dissociate) The process of increasing their expression is induction. Ex. ) allolactose is an inducer molecule that binds to the lac repressor causing it to dissociate from the operator. Gene products that decrease in concentration in response to a molecular signal are referred to as repressible.
