© 2004 Wadsworth – Thomson Learning Chapter 5 Metabolism of Microorganisms

© 2004 Wadsworth – Thomson Learning Metabolism in the cell Figure 5.1

© 2004 Wadsworth – Thomson Learning Biosynthesis in a cell Composition of cell –protein –RNA –DNA –Lipid –Lipopolysacharide –Peptidoglycan –Glycogen –Small molecules –Ions Figure 5.2

© 2004 Wadsworth – Thomson Learning Transport into the cell Outer membrane –pass through porin small size concentration gradient Cell wall –mesh-like –diffuse through Cell membrane –transporters Figure 5.3

© 2004 Wadsworth – Thomson Learning Oxidation/Reduction Reactions Reducing power used in metabolism –Oxidation loss of electrons –Reduction gain of electrons –reactions linked one molecule reduced one molecule oxidized Figure 5.5

© 2004 Wadsworth – Thomson Learning ATP: Biological Energy Adenosine triphosphate –negative charged phosphates repel –high energy bonds hold together –breaking bond to remove phosphate releases energy ATP –high energy ADP –low energy Figure 5.6

© 2004 Wadsworth – Thomson Learning Substrate level phosphorylation ADP obtains phosphate from metabolic intermediate –molecule which has a high energy bond ATP is formed Figure 5.7

© 2004 Wadsworth – Thomson Learning Glycolysis Start –6-carbon sugar (glucose) Energy input –two phosphorylations –2 ATP used for each glucose Cleave –two 3-carbon molecules Figure 5.9

© 2004 Wadsworth – Thomson Learning Glycolysis Reductions –two NAD+ are reduced –produce electron carriers Substrate level phosphorylation –2 ATP produced for every glucose Figure 5.9

© 2004 Wadsworth – Thomson Learning Glycolysis Dehydration –water removed Substrate level phosphorylation –2 more ATP produced End products –2 pyruvates –3-carbon molecules Figure 5.9

© 2004 Wadsworth – Thomson Learning Tricarboxylic Acid Cycle TCA or Krebs cycle Cycle –intermediates change from one form to another Converts Pyruvate to –CO 2 –Reducing power NADH FADH 2 used in electron transport for additional ATP synthesis –ATP Figure 5.10

© 2004 Wadsworth – Thomson Learning Pentose Phosphate Pathway Production of necessary precursors –Ribose-5-phosphate –Erythrose-4-phosphate Production of electron carriers –NADPH Figure 5.11

© 2004 Wadsworth – Thomson Learning Chemiosmosis Electron transport chain Generating a Proton gradient –protons pumped across membrane –occurs as electrons are transported from one carrier to another –high concentration outside of membrane Figure 5.8

© 2004 Wadsworth – Thomson Learning Chemiosmosis Generating ATP –Gradient drives ATPase synthesis of ATP from ADP and phosphates –Electron acceptor drives electron transport Oxygen (aerobic respiration) Sulfates, Nitrate, Fumarate (anaerobic respiration) Figure 5.8

© 2004 Wadsworth – Thomson Learning Biosynthesis Construct small molecules –Building blocks for macromolecules Uses products of catabolism –Precursor metabolites –ATP –Reducing power Figure 5.12

© 2004 Wadsworth – Thomson Learning Polymerization and Assembly Formation of macromolecules –DNA –RNA –Proteins –Polysaccharides –Peptidoglycan Assembly of cellular structure –Self-assembly— spontaneous –Enzyme-catalyzed Figure 5.13

© 2004 Wadsworth – Thomson Learning Anaerobic metabolism Anaerobic respiration –Electron transport –Final electron acceptor other than oxygen Fermentation –Substrate-level phosphorylation

© 2004 Wadsworth – Thomson Learning Fermentation No chemiosmosis Energy from glycolysis Conversion of pyruvate to other product –lactic acid –ethanol –mixed acids Figure 5.14

© 2004 Wadsworth – Thomson Learning Classification by nutrition Heterotrophs –Definition: Different feeders –Organic compounds as source of carbon Autotrophs –Definition: self-feeders –CO 2 as source of carbon Chemotrophs –Definition: chemical feeders –Energy and reducing power from chemical reactions Phototrophs –Definition: light feeders –Energy and reducing power from light energy

© 2004 Wadsworth – Thomson Learning Photosynthesis Synthesis of precursor metabolites From CO 2 Calvin-Benson Cycle Figure 5.15

© 2004 Wadsworth – Thomson Learning Photosynthesis Anoxygenic photosynthesis –Cyclic photophosphorylation –light energy activates electron –electron transport chain- proton gradient –produces ATP Figure 5.16

© 2004 Wadsworth – Thomson Learning Photosynthesis Oxygenic photosynthesis –Noncyclic –two levels of electron activation by light –water is source of electron –results in O 2 production Figure 5.17

© 2004 Wadsworth – Thomson Learning Regulation of metabolism Purpose –Ensure optimal amount of end products –Increase cell’s efficiency Types of Metabolic regulation –Enzyme regulation Gene regulation Activity regulation –allosteric activation –feedback inhibition

© 2004 Wadsworth – Thomson Learning Enzyme regulation Allosteric activation –product binds enzyme at allosteric site –inactivates enzyme Figure 5.18 Figure 5.20

© 2004 Wadsworth – Thomson Learning Enzyme regulation Feedback inhibition –multiple steps in metabolic pathway –end product inhibits enzyme earlier in pathway Figure 5.17