BIOLOGY 1A03 Chapter Notes - Chapter 17: Lac Repressor, Galactoside, Lac Operon

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Xudong Zhu

Document Summary

Chapter 17: control of gene expression in bacteria. Gene expression can be controlled at three levels: transcription, translation, post-translation (protein activation) Transcriptional control by a regulatory protein can be negative or positive: negative control prevents transcription, positive control increases the transcriptional rate. Many regulatory proteins bind to specific sites in dna: each regulatory protein has a distinct amino acid sequence so each binds to different dna sequences. Gene expression occurs when a gene product is actively being synthesized and used in a cell. Regulation of gene expression is critical to the efficient use of resources and so to survival. Escherichia coli has served as an excellent model organism for the study of prokaryotic gene regulation. Transcription and translation of genes in bacteria were predicted to be triggered by specific signals from the environment. Gene expression can be controlled at any step between the synthesis of rna and the activation of the final gene product: dna mrna protein activated protein.