BIOLOGY 1A03 Lecture Notes - Lecture 28: Lactose Permease, Operon, Repressor

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

Document Summary

When e. coli cells are in an environment that contains both glucose and the disaccharide lactose, bacteria will metabolize all the glucose before switching to utilizing lactose as a fuel source. This is an example of a highly regulated process. In this case, the control of enzyme production is regulated at the transcriptional level. Transcription in many genes in the e. coli genome are turned-on to accommodate for this chance in nutrient source. In particular, two important cues can be detected by e. coli cells. These include changes in glucose levels and the 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 protein. These two proteins are not detectable when the e. coli cells are utilizing glucose as a primary nutrient source, but are soon expressed as they are required for the transport and metabolism of lactose.