BIO 1140 Lecture Notes - Lac Operon, Regulatory Sequence, Trp Operon
22 Dec 2012
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Document Summary
The main control is at the level of transcription. Additional controls are at the post-transcriptional, translational, and post-translational levels. At the level of transcription, trans-acting factors interact with cis-acting sequences. There is a balance between activation and repression determines how much regulation occurs at the level of transcription. There are changes in the environment or changes in nutrient intake. Changes occur in the make up of the cell in response to signals. In prokaryotes, many genes are organized into clusters (transcription units) that are implicated in a single function. At a smaller scale, many genes are organized into operons (one or more operons may be found within a transcription unit) The operon can be considered as a unit of transcription with several genes controlled by a single promoter. An operon is effectivey a cluster of genes and dna sequences involved in their regulation.
