BIO230H1 Lecture Notes - Lecture 3: Prophage, Synthetic Biology, Chromosome
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BIO230H1 Full Course Notes
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Negative regulation: competition between rna polymerase and repressor protein for promoter binding. Positive regulation: activator protein recruits rna polymerase to the promoter to activate transcription. Typically close to the transcriptional start site of prokaryotic genes: e. g. , lac operon. However, regulatory elements can also be found: far upstream of gene, downstream of gene (eukaryotes, within gene (introns in eukaryotes) Some regulatory elements are distant from the transcriptional start site and influence transcription by dna looping: e. g. , ntrc protein, dna looping allows ntrc to directly interact with rna polymerase to activate transcription from a distance. Different types of transcriptional circuits exist and control various biological processes; combinations of regulatory circuits combine in eukaryotic cells to create exceedingly complex regulatory networks. Scientists can construct artificial circuits and examine their behaviour in cells (synthetic biology) Positive feedback loop: gene a allows protein a to be made, which goes back and activates itself further, basis for cell memory.
