BIOLOGY 1A03 Lecture Notes - Lecture 10: Growth Medium, Tetrameric Protein, Repressor

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Rosa Da Silva

Document Summary

Unit 1: responses to the environment: coli cells receive environmental cues. The metabolic shift in nutrient source utilization is tightly regulated in bacteria such that they are able to quickly upregulate the expression of genes that produce lactose-metabolizing enzymes when glucose is no longer available. Control of enzyme production is regulated at the transcriptional level. Two important cues can be detected by e. coli: changes in glucose levels, presence of lactose. As e. coli cells transition from glucose to lactose metabolism there is a concomitant increase in the amount of detectable beta-galactosidase and lactose permease proteins. These two gene products are not expressed until glucose is fully depleted from the medium. Interestingly, once glucose is depleted and the bacterial cells start utilizing lactose, there is also an increase in the expression of b-galactosidase and lactose permease. In addition to glucose possibly inhibiting the expression of these gene products, could lactose then induce their expression.