LIFESCI 3 Lecture Notes - Lecture 17: Adenylyl Cyclase, Lac Repressor, Dna-Binding Domain
Document Summary
Regulation of the lac operan: positive control: overview, only occurs when glucose is available, occurs simultaneously with negative control. 2 interactions: overview, gene expression is regulated through feedback loops, proteins change shape so that they can or cannot bind dna, (1) effector molecule removes repressor, ex. Allolactose (effector) binds lac repressor comes off the promoter transcription occurs: (2) effector molecule adds an activator, ex. camp (effector) binds cap (activator) transcription occurs. Cap-camp complex binds to dna frequent transcription of lac operan cell uses lactose if lactose is present: turns negative regulation off & positive regulation on. Transcription factors: definition, any protein that binds the dna. Rna polymerase fall off: called the attenuator , attenuation of transcription occurs, the attenuated mrna is much shorter than the. A: constitutive expression in the presence of lactose regardless of glucose levels: don"t need camp to recruit cap. Q: you"ve introduced a mutation into cap that causes it to lose its ability to bind camp.
