BIO230H1 Lecture Notes - Lecture 3: Lambda Phage, Lac Repressor, Lac Operon

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19 Oct 2013
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BIO230H1 Full Course Notes
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BIO230H1 Full Course Notes
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Note: the first few slides are review from the previous lecture and so, i will not be writing those things down! I will be starting these notes from slide 7. Some regulatory elements are distant from the transcriptional start site and influence transcription. It turns out that the lac operon is also regulated by operator sequences far away from the operon. There are 2auxiliary operators in the e. coli genome that can be bound by the lac repressor. They influence transcription of the lac operon through dna looping (more common in eukaryotes than prokaryotes). This dna looping is what allows the lac repressor bind to operator sequences far away from the operon transcription start site. It likely increases the affinity of the lac repressor to the lac promoter (since it is binding to 2 operators rather than one). It may also affect the concentration of the repressor in the environment.