BIOL 2051 Chapter : Part Of Ch10 And Ch12 Fall10
Document Summary
Regulating gene expression: microbes respond to changing environment. Alter proteins produced: must sense their environment, receptors on cell surface, must transmit information to chromosome. Alter gene expression: change transcription rate, change translation rate. 1. sensor kinase protein in cm: binds to signal, food, chemical cue, activates itself via, cytoplasmic response regulator. Takes phosphate from sensor: binds chromosome, alters transcription rate of multiple genes. The amount of an enzyme in the cell can be controlled by decreasing (repression: or increasing (induction) the amount of mrna that encodes the enzyme. For negative control of transcription, the regulatory molecule is called a repressor protein and it functions by inhibiting mrna synthesis. Lactose (milk sugar) is used as nutrient source: cannot pass through cell membrane lactose permease allows entry, disaccharide lactose must be cleaved into monosaccharides to be digested, b-galactosidase cleaves lactose. The lac operon is an example of negative control of transcription. (allolactose) http://www. wwnorton. com/college/biology/mbio/animations/main. asp?chno=ch10a01.
