BIOLOGY 1A03 Study Guide - Final Guide: Lactose Permease, Lac Operon, Beta-Galactosidase

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Lovaye Kajiura

Document Summary

Describe how bacterial cells organize functionally related genes into single transcriptional units. Identify how gene expression can be negatively and positively regulated. Examine how the outcomes of gene expression can be regulated based on environmental cues. Recall: e. coli cells in glucose and lactose, metabolizes glucose then switches to lactose. Metabolic shift tightly regulated > expression of lactose metabolizing genes turned on when only lactose is present. Control of enzyme production > transcriptional level regulation. Two cues that indicate translation to glucose and lactose metabolism: 1) changes in glucose levels, 2) presence of lactose. As e. coli transitions from glucose to lactose metabolism: increase in beta galactosidase and lactose permease proteins. Two proteins not detectable when e. coli cells use glucose primarily. Lactose permease: transport protein in cell membrane, allows for transport of lactose into bacterial cell. Beta galactosidase: cytoplasmically situated bacterial enzyme, cleaves imported lactose into glucose + galactose.