Biology 2581B Lecture Notes - Lecture 14: Lactose Permease, Lac Repressor, Lac Operon
26 Mar 2014
School
Department
Course
Professor
Document Summary
Biphasic growth curve: coli lac operon model. Interestingly, b-galacotosidase, the enzyme responsible for lactose metabolism is produced in phase ii, but not in phase i. The simple monosaccharide glucose, is preferred over the di-saccharide, lactose as a carbon and as an energy source. Two genes are critical for the breakdown of lactose into simpler sugars. Lactose passes through the membranes of the cell via an opening formed by the protein. Inside the cell, b-galactosidase splits lactose into galactose and glucose. The dilemma facing bacteria: unicellular cell so must be capable of extreme adaptation to changing, must not waste energy making products it does not need. So must be capable of switching genes on as needed or off when not needed. Different genes need different strategies for control: catabolic genes are involved with the breakdown of complex products into simpler ones, for example, ability to utilize lactose. So these genes only needed when the complex compound is present.
