Microbial Metabolism

Microbial Metabolism  Metabolism = change, pertains to all chemical reactions and physical workings of the cell or all the biochemical reactions that take place in a cell  metabolism of most living things are similar but there are some differences, depending on the organism Ex : Metabolic tasks required to double cell mass Bringing nutrients into the cell Catabolism Biosynthesis (or Anabolism) Polymerization Assembly Catabolism Anabolism Metabolites degrade, break bonds, convert large molecules into smaller component often produce energy synthesis of cell molecules and structures usually requires the input of energy compounds given off by the complex networks of metabolism Enzymes : Catalyzing the chemical reactions of life • How enzymes work? – Energy of activation Enzyme structure • simple enzymes consist of protein alone • conjugated enzyme (or haloenzyme) contain protein (apoenzyme) and nonprotein molecules (cofactors) active site = the site that accepts a substrate Cofactors supporting the work of enzymes • organic molecules coenzyme (e.g vitamin) perform a necessary alteration of a substrate • inorganic elements metal ions (Fe, Cu, Mg, Mn, Zn, Co, Se etc.) help bring the active site and substrate close together Allosteric enzymes active site have types of specific binding sites allosteric site bindin g effectors - change the conformation of enzyme at active site - results in a corresponding inhibition (activation) of enzyme activity Inhibitors prevent or slow down enzyme reactions by binding to the enzyme competitive structure resemble the normal substrate non-competitive structure not relate e.g CN-, Hg, As 10 • bacteriochlorophylls are the photosynthetic pigments in bacteria (a, b, c, d, e) • Wavelengths ranging from 400 to 650 nm Chlorophyll a Bacteriochlorophyll a 33 Sunlight is electromagnetic energy : it has Wavelike property : spectrum ranges from gamma rays ( < nm) to radio waves ( > km) : Visible light is a small part of electromagnetic spectrum: it is most important for photosynthesis 34 Particlelike property - photon - each photon has a fix amount of energy (short wavelength = high energy) 35 The Light Reactions Schematic of a Photosyst em 36 15 there are separate photosystems in plants, algae, and cyanobacteria Photosystem I (P700) Photosystem II (P680) their chlorophyll molecules are the same, but are surrounded by different proteins in others bacteria have only Photosystem II the photosystems are coupled by an electron transport ATP and NADP+ NADPH + H+ 37 38 Photosystem in bacteria 39 40 The simplest pathway that involves only PS I (P700) Electrons that leave the P700 reaction center chlorophyll cycle from Fd to the cytochrome complex and return to reaction center Produce ATP but not NADPH or O2 Cyclic electrons flow supplies the extra ATP required in the Calvin Cycle 41 How is the ATP made during the light reaction • Chemiosmosis : the coupling of exergonic electron flow down an ETC with endergonic ATP42 production • as electrons pass through the cytochrome complex, H+ ions are pumped into the thylakoid space • this leads to 1000-fold difference in H+ ion conc between the stroma and the thylakoid space • ATP synthase uses the downhill diffusion of H+ ions across the thylakoid membrane to produce ATP • in chloroplast, approx H+ions must diffuse through ATP synthase to make ATP molecule Splitting of water Movement of electrons H+ ions H+ ions 1.3 ATP 43 1.3 ATP MOLECULES OF MOLECULES OF MOLECULES OF MOLECULES OF MOLECULES OF 44 Phase one RuBP + CO2 + H2O rubisco 12 3-Phosphoglycerate 45 Phase two • phosphorylation followed by reduction • Consumes ATP and NADPH to produce six glyceraldehyde 3-phosphate molecules • only one glyceraldehyde REDUCTION 3-phosphate molecules exits the cycle 46 29 Phase three • RuBP (a 5-carbon sugar) is regenerated • requires ATP molecules • takes five glyceraldehyde 3-phosphate and rearranges them to make three 5-carbon sugars (RuBP) CO2 + 18 ATP + 12 NADPH Fructose-6-phosphate + 18 ADP 47 + 12 H+ + 11 H2O + 30