01:119:115 Lecture Notes - Lecture 16: Lactose Permease, Trp Operon, Histone Methylation
13 Jul 2016
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Document Summary
Prokaryotes and eukaryotes regulate gene expression in response to environmental conditions at level: bacterial gene expression regulated at transcription, eukaryotic gene expression regulated at many stages. In multicellular eukaryotes, gene expression regulates development and is responsible for differences in cell types. All cells in individual identical genetic info but have form and function because only subset of genes are expressed. Constitutive genes (= housekeeping genes) encode proteins that are always needed constantly transcribed e. g. enzymes involved in respiration: lac operon model: the basic concept, coli normal inhabitant of human intestine. Can adjust to changes in chemical environment (food eaten by host) If host drinks milk e. coli must be able to digest lactose in milk. 1: -galactosidase ( -gal) to hydrolyze it to glucose and galactose, galactoside transacetylase: used in lactose metabolism. Lactose permease (membrane transport carrier) to take lactose into cell. So 3 genes for lactose metabolism in e. coli.
