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Operons. Emily Foley, Gabrielle Yu, Deanna Liou, Katrina Torres. Components of Operons:. Promoter: a nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA Operator: a segment of DNA that acts as a “switch”
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Operons Emily Foley, Gabrielle Yu, Deanna Liou, Katrina Torres
Components of Operons: Promoter: a nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA Operator: a segment of DNA that acts as a “switch” -it is positioned between the promoter and enzyme-coding genes -controls the access of RNA polymerase to the genes Genes of operon: code enzymes using the mRNA
Operons An operon is made of a promoter, operator, and the genes they control. This segment of DNA produces an enzyme. A trp (for tryptophan) operon is an operon that produces tryptophan, an amino acid E. coli needs to synthesis for itself because it is not found in its food.
Repressors When enough tryptophan is present, the trp repressor will become active and the operon will turn off. For this to happen, the trp acts as a corepressor, fitting into the repressor to activate it. The trp repressor then binds to the operator, blocks RNA polymerase from attaching to the promoter, and prevents the trp operon from transcripting more genes.