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2/24/14Microbial MetabolismMetabolism of Energy ProductionMicrobial Metabolism - chemical reactions in a living cell- Many microorganisms have some of the same metabolic pathways as humans- Two types of metabolism Anabolism: building or synthesis reactionso how a cell makes proteins by putting amino acids together Catabolism: degradation/ breaking down reactionso bigger molecule breaks down into smaller molecules*ALL reactions require enzymesMicrobial metabolism- Energy production metabolism Catabolic – breaks down and extracts energy End result is ATP <– energy currency of the cello ATP can be obtained immediately Chemoheterotrophs (humans, many microbes)o Cellular Respiration (aerobic respiration)- Glycolysis- Krebs Cycle (TCA or Citric Acid Cycle)- Electron Transport Chain Microbes have other types of metabolism other than cellular respirationATP- ATP is made up of a sugar (ribose), a nitrogenous base (adenine), and a triphosphate groupEnergy Metabolism of MicroorganismsPathways- Cellular Respiration ADP+Pi What Cells Do with ATP- Anaerobic Respiration -Chemical Work- Fermentation -> -> (synthesizes molecules)- Chemolithotrophy *-Transport Work(Chemoautotrophy) (transport chemicals across- Photosynthesis ATP membranes)(no details covered) *uses most energy-Mechanical Work(movement of cell parts)ATP Production- Metabolic Pathways for ATP Production*1) Chemoheterotrophy: Cellular Respiration, Fermentation, Anaerobic Respiration- Oxidation of organic compounds (electron donor) Electrons contain the energy of a molecule Example donor : glucose*2) Chemolithotrophy (chemoautotrophy)- Oxidation of inorganic compounds (electron donor) Example donor: nitrite3) Phototrophy (photoautotrophy) photosynthesis- Photons used to boost electrons to higher energy levels which then are transferred to lower levels to produce ATP, uses sunlight Example donor: waterCellular Respiration – Aerobic Respiration- Complete breakdown of molecules- About 90% of microorganisms use this- Preferred molecule for making ATP: Carbohydrates Monosaccharide: Glucose- End up with carbon dioxide and water as low energy end productsCellular Respiration (Figure 8.12 in book)3 Parts1) Glycolysis – the splitting of glucose- Makes 2 ATP- End product is 2 pyruvic acids- 2 NADH are produced NADH is a temporary energy storage molecule It is used later on in cellular respiration2) Krebs Cycle – circular cycle- Pyruvic acid starts the cycle- Makes 2 ATP- Carbon dioxide is given off (waste gas)- FADH2 and NADH are produced Both are temporary holdings of energy and are used later on3) Electron Transport Chain – shuttles electrons from molecule to molecule- NADH and FADH2 start the electron transport chain- Slowly extracts electrons- Oxidation Reduction Reaction- Oxygen gas is needed in the last step to make water Oxygen is the final electron acceptor- Lots of ATP is made (34)Anaerobic Respiration- Only carried out by a few species of bacteria (archea)- Same as cellular respiration except: No oxygen used in last step of electron transport chain Uses other inorganic compounds- Nitrate (NO3-) – (nitrate reducing bacteria)– NO3- -> NO2- + H2O- Sulfate (SO4--) Fermentation- Many microbes depend on it- Still uses organic molecules- Anaerobic – When no oxygen is around- Partial catabolism of carbohydrates- Energy yield much smaller than cellular respiration – doesn’t make as much ATP- Glycolysis is present – needs NAD! Only substrate level phosphorylation  No Krebs Cycles or Electron Transport Chain used! *the big difference between fermentation and cellular respiration*- Organic end products given off – lots! Acids, alcohols, gasses, ketones, aldehydeso lactate, Y*Replenishment of NAD+*Needed to keep glycolysis running- Pyruvate converted to other products (end products) Results in more

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KSU BSCI 20021 - Microbial Metabolism

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