BIOCHEM 2B03 Lecture Notes - Structural Gene, Penicillin, Starch
6 Sep 2013
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Document Summary
The modern idea of the gene was developed from studies of bacterial metabolism. Jacob and monod originators of the modern idea of gene transcription: 1961 postulate the existence of mrna. Base composition would reflect that of dna. Heterogenous in mass (reflecting myriad proteins found in cells) High turnover rate permitting regulated gene function able to associate with ribosomes site of protein synthesis. Evidence for regulation and the existence of mrna. Enzyme induction: bacteria make certain enzymes in variable rates responding to changes in environment. Investigation of inducible systems in bacteria e. coli. Synthesis of an enzyme that acts on compound a is induced by compound a: compound a is called an inducer. Constitutive proteins: synthesized at a constant rate (not regulated) Eg/ housekeeping proteins : ribosomal proteins (10,000 copies/cell) Inducible proteins: synthesized at variable rates dependent on cells circumstances (regulated) Eg/ regulatory proteins (often rate <10 copies per cell: -galactosidase, galactoside permease, thiogalactoside transacetylase.
