BIOL 1107 Lecture Notes - Lecture 3: Adenylyl Cyclase, Galactoside, Operon
Document Summary
In bacteria, gene expression can be controlled at three levels: transcription, translation, or post-translation (protein activation). Changes in gene expression allow bacterial cells to respond to environmental changes. Transcriptional control can be negative or positive. Negative control occurs when a regulatory protein prevents transcription. Positive control occurs when a regulatory protein increases the transcription rate. Introduction: a cell does not express all of its genes all of the time. Instead, they are very selective about the genes they express, how strongly they are expressed, and when they are expressed: 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 thus survival. Control of gene expression allows e. coli to respond to its environment and switch its use of sugars: gene expression in bacteria was predicted to be triggered by specific signals from the environment.
