BIOL336 Ch 3 Metabolism (SP25) PDF

Ch 3 Metabolism BIOL336 SP25 Dr. Purple  3.1 Defining the Requirements for Life Metabolism: All biochemical reactions needed for life Energy is neither created nor destroyed Cells conserve energy by conversion into a form that can do work Generate adenosine triphos...

Ch 3 Metabolism BIOL336 SP25 Dr. Purple  3.1 Defining the Requirements for Life Metabolism: All biochemical reactions needed for life Energy is neither created nor destroyed Cells conserve energy by conversion into a form that can do work Generate adenosine triphosphate (ATP) to store energy and fuel processes  3.1 Defining the Requirements for Life Energy Catabolic pathways: exergonic cellular processes that generate free energy Anabolic pathways: endergonic cellular processes in which cellular synthesis requires energy 3.1 Defining the Requirements for Life Figure 3.3 Classification of Metabolic Types Based on Energy Sources 3.4 Cellular Energy Conservation Adenosine Triphosphate (ATP) Most important energy-rich phosphate compound Two high energy phosphate bonds  3.4 Cellular Energy Conservation Energy-Rich Compounds Several others have energy-rich phosphate or sulfur bonds Not all phosphate bonds are energy-rich Figure 3.8 Energy-Rich Bonds in Compounds That Conserve Energy in Microbial Metabolism II. Catabolism: Chemoorganotrophs Two. 3.6 Glycolysis, the Citric Acid Cycle, and the Glyoxylate Cycle 3.7 Principles of Fermentation 3.8 Principles of Respiration: Electron Carriers 3.9 Principles of Respiration: Generating a Proton Motive Force  3.6 Glycolysis Glycolysis Nearly universal pathway for glucose catabolism that oxidizes glucose to pyruvate Two stages 3.6 The Citric Acid Cycle Citric Acid Cycle Pyruvate oxidized to CO2 Makes important precursor molecules along the way  3.6 The Glyoxylate Cycle Glycoxylate Cycle Uses C2 compounds (e.g. acetate) 3.7 Principles of Fermentation Fermentation of glucose involves substrate-level phosphorylation and redox balance via pyruvate reduction + excretion as waste 3.8 Principles of Respiration: Electron Carriers Respiration: a series of chemical reactions that break down glucose to produce ATP electrons transferred from reduced electron donors to external electron acceptors (e.g., O2 ) NADH and FADH2 produced in glycolysis and citric acid cycle must be reoxidized for redox balance In respiration, reoxidation occurs during electron transport Occurs in cytoplasmic membrane Forms electrochemical gradient (usually protons) that conserves energy through ATP synthesis  3.8 Principles of Respiration: Electron Carriers Other electron carriers: NADH dehydrogenases Flavoproteins Cytochromes Other Iron Proteins Quinones  3.9 Principles of Respiration: Generating a Proton Motive Force (2 of 11) Electron Transport Electron movements are exergonic, providing free energy to pump protons to outer surface of membrane Generates proton motive force Figure 3.20 Structure and Function of the Reversible A TP Synthase (ATPase) in Escherichia Coli  Cellular Respiration Summary Cellular respiration has 3 main steps: Glycolysis Pyruvate oxidation and citric acid cycle (AKA Krebs cycle) Oxidative phosphorylation Figure 3.21 Energetics in Fermentation and Aerobic Respiration 3.10 Anaerobic Respiration and Metabolic Modularity Respiration in Escherichia coli Can optimize under multiple conditions With organic carbon source, grows fastest by aerobic respiration Grows faster with nitrate respiration than fermentation (a) Aerobic respiration (b) Nitrate reduction Figure 3.23 Respiration and Nitrate-Based Anaerobic Respiration in Escherichia Coli 3.10 Anaerobic Respiration and Metabolic Modularity Respiration in Escherichia coli For any electron donor, aerobic organisms always conserve more energy and will outcompete anaerobic organisms O2 consumed very quickly Anoxic habitats and anaerobic microbes widespread 3.11 Chemolithotrophy and Phototrophy Phototrophy Can be oxygenic or aoxygenic Purple bacteria are anoxygenic prototrophs common in anoxic aquatic environments produce photosynthetic reaction center that converts light into chemical energy reaction centers contain photopigments (e.g., chlorophylls, bacteriochlorophylls) photopigments absorb light, transfer energy to photosynthetic reaction center, forms proton motive force that ATP synthase uses to make ATP  Four. Biosynthesis IV. 3.12 Autotrophy and Nitrogen Fixation 3.13 Sugars and Polysaccharides 3.14 Amino Acids and Nucleotides 3.15 Fatty Acids and Lipids  3.12 Autotrophy and Nitrogen Fixation Nitrogen Fixation Nitrogen needed for proteins, nucleic acids, other organics Most microbes obtain this nitrogen from “fixed” nitrogen (ammonia, NH3 , or nitrate, NO3 − ) Many prokaryotes can conduct nitrogen fixation: form ammonia (NH3 ) from gaseous dinitrogen (N2 ). (Figure 3.28)  3.14 Amino Acids and Nucleotides Amino acid and nucleotide biosynthesis typically use long, multistep pathways. Monomers of Proteins: Amino Acids If amino acids are not obtained from environment, synthesized from glucose or other carbon sources Grouped into structural families based on shared biosynthetic steps Carbon skeletons come from intermediates of glycolysis or citric acid cycle  3.15 Fatty Acids and Lipids Fatty Acid Biosynthesis Can be unsaturated, branched, or contain odd numbers of carbon atoms Varies between species and at different temperatures lower temps: shorter, more unsaturated higher temps: longer, more saturated Bacteria most commonly have C12 -C20lipids