BIOL 2153 Chapter : Genetics Outline
Document Summary
Operons as models for studying gene expression: inducible operon, regulatory substance called an inducer causes changes in gene expression referred to as induction, typically catabolic pathways are induced, examples: lac operon, ara operon lac operon. Trp repressor trpr codes for the trp repressor regulatory gene for the trp operon an aporepressor protein binds 2 tryptophans before trpr can bind to the operator. Attenuation creates short length transcripts from trpl that do not fully code for the tryptophan biosynthesis enzymes. Allows levels of expression to vary depending on tryptophan concentration. The more tryptophan, the greater number of short transcripts, and therefore less tryptophan made by the cell. If no tryptophan is present, then only full-length transcripts that include the. 5 trp structural genes are made. trpl trpl. Arabinose is the inducer causing an allosteric shift in arac allowing one subunit of arac to bind to arai1 and another subunit to bind to arai2.
