The relationship of Krebs cycle to protein, carbohydrate, lipid and nucleic acids metabolism. Integration of metabolic pathways; Turnover rates and metabolic pathwaysl Turn – over rates and metabolic pools; Intrinsic and extrinsic control of metabolic pathways; Regulation of enzymes of metabolic pathways–feedback inhibition versus enzymes synthesis, catabolite repression and product repression, the lactose operon and the arabinose operon; Identification of different regulatory mechanisms in metabolic pathways.