BIOL 261 Chapter : Chapter 8 Class Notes Regulation Of Gene Expression
15 Mar 2019
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Two major levels of regulation in the cell: one controls the activity of preexisting enzymes, posttranslational regulation, very rapid process (seconds, feedback inhibition: end product binds to an early enzyme in the pathway at the allosteric site. This changes the shape of the active site and blocks the enzyme. Too much end product causes feedback inhibition: one controls the amount of an enzyme, happens at the gene level, regulate level of transcription, regulate translation, slower process (minutes, repressor proteins: bind to the dna. I gene: codes for the repressor protein in the lac operon binds to the operator to block transcription because the cell doesn"t have any lactose that needs to be broken down. When the cell has lots of lactose, the some lactose is converted allolactose. Allolactose is the inducer and binds to the repressor protein and prevents it from binding to the operator thus inducing transcription of the lac operon.
