01:119:115 Chapter Notes - Chapter 18: Lac Operon, Trp Operon, Lactose Permease
28 Mar 2016
School
Department
Course
Professor
Document Summary
Prokaryotes and eukaryotes regulate gene expression in response to environmental condiions at level: bacterial gene expression regulated at transcripion, eukaryoic gene expression regulated at many stages. In mulicellular eukaryotes, gene expression regulates development and is responsible for diferences in cell types. All cells in individual idenical geneic info but have form and funcion bc only subset of genes are expressed. Consituive genes (= housekeeping genes) encode proteins that are always needed constantly transcribed e. g. enzymes involved in respiraion. Needs 3 proteins: lactose permease (membrane transport carrier) to take lactose in cell, -galactosidase ( -gal) to hydrolyze it to glucose and galactose, galactoside transacetylase: used in lactose metabolism. Either all genes are on or all are of. The 3 genes are: controlled together: part of an operon, next to each other on chromosome, share a single promoter nucleoide sequence in dna, transcribed into single, coninuous mrna.
