Chap4Metab13thedition

Theycan becaughtbyacceptorsatvariouslevelsbelow

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Unformatted text preview: H nicotinamide adenine dinucleotide Coenzyme involved in Coenzyme involved in oxidation/reduction reactions Phases of Metabolism Phases of Metabolism Phases of Metabolism Phases of Metabolism • I. Catabolism (fueling): Phase 1 • • II. Anabolism: Phases (Subdivisions) 2­4 below • • Degradative metabolism, exergonic, oxidative, ∆ G = (­), “spontaneous” Biosynthetic metabolism, endergonic, reductive, ∆ G = (+) Subdivisions: 1. Fueling 2. Biosynthesis 3. Polymerization 4. Assembly Catabolic Anabolic Fueling Reactions Biosynthetic Reactions Polymer­ izations Assembly reactions Lipid Inclusion Fatty Acids (~8) Lipopoly saccharide Precursor metabolites PO 4 3­ Glucose I Metabolic energy Envelope SO 4 2­ Glycogen Flagella Murein Reducing power NH 3 C­1 Units Sugars (~25) Amino Acids (~20) II III Protein RNA Nucleotides (~8) IV Pili Cytosol Poly­ Ribosomes DNA Fueling Products Building Blocks Nucleotide Macro­ molecules E. coli structures I Fueling (Catabolism) Oxidation-Reduction Reactions o Provides 3 things for the cell o Energy (from oxidation of energy source in a complete oxidation-reduction reaction) o “C” skeletons: 12 intermediates (3 central pathways: EM, Krebb’s, Pentose) o Reducing Power: ex NADH + H+ The pathways of catabolism have a ∆ G = (-) and are spontaneous II Biosynthesis: uses products of catabolism: Energy, reducing power, and C skeletons o Biosynthesis involves those reactions which use the “C” skeletons to make subunits of the macromolecules o These are 12 key precursor metabolites that produce the correct numbered “C” skeletons for biosynthesis of the subunits: o 20 Amino Acids o 4 Ribonucleotides o 4 Deoxyribonucleotides o Monosaccharides, N-Acetylglucosamine, NAcetylmuramic acid, Fatty acids & Glycerol Example: Biosynthetic pathway Figure 1 Tryptophan Biosynthesis Figure 3 Families of Amino Acids • Chorismate L-tryptophan • Phrephanate L phenyl alanine • L tyrosine II Biosynthetic Reactions o Biosynthetic Reactions produce the building blocks of polymerization reactions; they also produce cofactors and related compounds including signaling molecules called Alarmones. The hundreds of biosynthetic reactions are grouped into functional units called Biosynthetic Pathways each consisting of from one to a dozen sequential reactions that produce one or more building blocks. o Biosynthetic pathways may be linear, branched, or in some cases, interconnected; each pathway is controlled en bloc. o Tryptophane family synthesized in branched biosynthetic pathway (previous slide) III Polymerization Reactions o Polymerization Reactions consist of the directed, sequential linkage of activated (next slide) molecules into long (sometime branched) chains. o All the macromolecules are formed from the building blocks that include 20 amino acids, 8 nucleotides, numerous sugars, and fatty acids o Polymerization of building blocks into proteins, RNA, DNA and glycogen occur inside the cell, whereas the final steps of their assembly into lipopoly...
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