BIOSC 0160 Lecture 7: Bio 2 Unit 2 Notes
Document Summary
Bio 2 unit 2 ch 16 r: 336-341. 16. 1 prokaryotic gene expression is regulated in operons: Proks conserve e by only making certain proteins when necessary: Prok regulation options: response to envt signals, and waste least amount of e. Decrease rate of transcription of mrna for that protein. Hydrolyze the mrna after its made, preventing translation. Prevent translation of the mrna at the ribosome. Hydrolyze the protein after it is made. Expression begins at promoter, but not all promoters are always active. This is decided by two types of regulatory proteins the bind to dna promoter. Repressor proteins, bind at repressor binding site=negative regulation: prevents transcription. Activator proteins, binds at activator binding site=positive regulation: stimulate transcription. Lactose=b-galactoside (a disacharide containing galactose b-linked to glucose. Enzymes involved in uptake and metabolism of lactose: B-galactoside permease moves the sugar into the cell. B-galactosidase: hydrolyzes lactose to glucose and galactose. B-galactoside transacetylase: transfers acetyl groups from acetyl coa to certain b-galactosides.