1Anabolism• synthesis of complex molecules and cellular structures• turnover– continual degradation and resynthesis of cellular constituents• rate of biosynthesis approximately balanced by rate of catabolism• requires much energyFigure 10.123Principles Governing Biosynthesis• macromolecules are synthesized from limited number of simple structural units (monomers)– saves genetic storage capacity, biosynthetic raw material, and energy• many enzymes used for both catabolism and anabolism– saves materials and energy4More principles…• catabolic and anabolic pathways are not identical, despite sharing many enzymes– permits independent regulationFigure 10.25More principles…• breakdown of ATP coupled to certain reactions in biosynthetic pathways– drives the biosynthetic reaction to completion• in eucaryotes, anabolic and catabolic reactions located in separate compartments– allows pathways to operate simultaneously but independently6More principles…• catabolic and anabolic pathways use different cofactors– catabolism produces NADH– NADPH used as electron donor for anabolism• large assemblies (e.g., ribosomes) form spontaneously from macromolecules by self-assembly7Calvin cycle• in eucaryotes, occurs in stroma of chloroplast• in cyanobacteria, some nitrifying bacteria, and thiobacilli, may occur in carboxysomes– inclusion bodies that contain ribulose-1,5-bisphosphate carboxylase (rubisco)• consists of 3 phases8The Carboxylation Phase• rubisco catalyzes addition of CO2to ribulose-1,5-bisphosphate (RuBP), forming 2 molecules of 3-phosphoglycerateFigure 10.39The Reduction Phase• 3-phospho-glycerate reduced to glyceraldehyde 3-phosphateFigure 10.410The Regeneration Phase• RuBP regenerated• carbohydrates (e.g., fructose and glucose) are producedFigure 10.411Summary6CO2+ 18ATP + 12NADPH + 12H++ 12H2O↓glucose + 18ADP + 18Pi+ 12NADP+12Synthesis of Sugars and Polysaccharides• gluconeogenesis– used to synthesize glucose and fructose from noncarbohydrate precursors• sugar nucleoside diphosphates– important in synthesis of other sugars, polysaccharides, and bacterial cell walls13Gluconeogenesis• generates glucose and fructose– most other sugars made from them• functional reversal of glycolysis– 7 enzymes shared – 4 enzymes are unique to gluconeogenesis14Figure 10.515Anaplerotic CO2fixationphosphoenol-pyruvate (PEP)carboxylase:PEP + CO2→oxaloacetatepyruvatecarboxylase:pyruvate +CO2→oxaloacetateFigure