BIOMG 1350 Lecture Notes - Lecture 18: Lac Operon, Repressor, Allolactose

• School: Cornell University
• Department: Molecular Biology and Genetics
• Course: BIOMG 1350
• Professor: Discussion

Document Summary

Goes through many steps in the transcriptional processes. Most common control point for development (long-term decisions) Contains sequences recognized and bound by rna polymerase. Promoters vary in strength of binding to rna polymerase. Activity can be enhanced by transcriptional activators. Can act together to provide highly sensitive transcriptional regulation. E. coli uses glucose as an energy source, but in rare cases it can break down lactose when it really needs to. Lac genes are only on when only lactose is on; off whenever glucose is present. When no lactose is present, a repressor molecule attaches to the operator sequence. When lactose is present, a metabolite of lactose, allolactose, removes the repressor. Not sufficient to start transcription because the promoter is weak. In case of high lactose + low glucose. Both cap and repressor removal act together to allow rna polymerase to bind. Transcription regulators contain a variety of dna binding motifs. Eukaryotic transcription is more complex than prokaryotic transcription.