BIO 207c 1st Edition Lecture 4Chapter 7Microbial MetabolismMetabolismI. Metabolisma. The sum total of all chemical reactions in a celli. Reaction types:1. Anabolic- building of large molecules from small ones requiring energy2. Catabolic- breaking down large molecules into small ones releasing energyb. Functions of metabolism i. Assembles small molecules into larger onesii. Break larger molecules down to form simpler onesiii. Store energy in the form of ATPEnzymesI. Abouta. Most are proteinsb. Act to lower the activation energy (energy required to start a chemicalreaction) of a reactionc. This allows for chemical reactions to proceed at temperatures conducive to lifed. Are catalysts because they speed up the rate of reactionse. Does so by interacting with substratef. This interaction is very specific-one substrate to one enzymeg. Enzyme catalyzed reactions can be summarizedh. A union forms between the enzyme and the substrate at the enzyme’s active sitei. The appropriate reaction occurs on the substratej. Product is formedII. Coenzymesa. Organic compounds that work together with an enzymeb. Assist in moving a chemical group from one substrate to anotherc. May act as carriers for hydrogen atoms, electronsd. Many are derived from vitamins which is why vitamins are necessary for good healthIII. Regulation of Enzyme Actiona. Regulation of Enzyme Actionb. Different types of enzymesi. Constitutive enzymes- 1. always present in constant amount2. Not dependent on amount of substrateii. Regulated enzymes1. Production is turned on or off depending on the amountof the substrate presentc. Can be influenced by environmentd. Temperature, pH, and osmotic pressure can affect enzymese. In certain environments enzyme structure will break down-denaturationf. When enzyme loses its structure it loses its functiong. Chemical reactions will not occur leading to cell deathMetabolic PathwaysI. Metabolism is a multistep processa. Each step has its own enzymeb. Reason is the product of one reaction may be the substrate of the nextPursuit and Utilization of EnergyI. Metabolism requires energya. Cells require a constant input of energyb. Energy required comes from light or from chemical bonds (when bonds break they release energy)c. Energy is stored in form of ATP (adenosine triphosphate)Energy of CellsI. Energy is stored in chemical bondsa. Energy is managed by the forming and breaking of those bondsi. Exergonic reactions- release energy that is then available for cellular workii. Endergonic reactions- require energy to proceedb. Cells extract energy from nutrientsi. Energy released by exergonic reactions is stored in ATPii. ATP fuels all endergonic reactions of the cellOxidation-Reduction ReactionsI. Oxidation-II. Reduction-a. Occurs in pairs with carrier molecules such as NAD and FAD carrying electronsb. Redistribution of energy ultimately leads to the formation of ATPc. To follow the electrons-i.Pursuit and Utilization of EnergyI. ATPa. Considered to be a high energy yielding moleculeb. When bond at terminal phosphate is broken, energy is released which can be used to drive chemical reactionsc. Constantly being formed in cellCatabolismI. Nutrient for catabolism most often used by bacteria is GLUCOSEa. 3 Types of catabolismi. Aerobic- ii. Anaerobic-iii. Fermentation-b. Aerobic Respiration i. Consists of 3 steps-glycolysis, Kreb’s cycle, electron transport chain/chemiosmosis1. Glycolysis-2. Oxidation of glucose-3. Produces-ii. Kreb’s cycle1. Pyruvic acid is converted into Acetyl CoA, which then enters the cycle2. Productsiii. Aerobic respiration1. Electron transport chain/chemiosmosis2. Electrons from NADH and FADH2 are passed down a series of carrier molecules3. Energy supplied by this process pumps H+ across the plasma membrane, creating a concentration gradient4. At a certain concentration, H+ will diffuse back into the cell through ATP synthase, producing ATP5. At end, oxygen is present and will combine with the hydrogen to form water6. If oxygen is not present, the process stops7. Productsiv. Anaerobic respiration1. Process is similar to that of aerobic respiration except for the final electron acceptor2. An inorganic molecule other than water is the electron acceptor3. Nitrite and nitrate are commonly used4. Produces fewer ATP than aerobic respirationv. Fermentation1. Incomplete oxidation of glucose2. Uses organic compounds as final electron acceptors3. Produces least amount of ATP4. In the process pyruvic acid is formed, then, depending on microbe/environment, various products result5. Fermentation is important to: Catabolism of Noncarbohydrate CompoundsI. Polysaccharides are broken down into simpler sugarsII. Lipids are broken down into their glycerol and fatty acid components and their products can enter the Kreb’s cycleIII. Proteins are broken down into amino acids which are altered and can enter the Kreb’s