BIOL_2051_ch13_and_ch14_notes - Chapter 13 Energetics...

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Chapter 14 Sun is ultimate energy source Photosynthesis used by many plants and bacteria Captures light energy from the sun and stores it as chemical energy Heterotrophy Uses captured chemical energy builds other chemicals Waste Each step of photosynthesis and heterotrophism gives off heat energy Metabolism Catabolism Breaking down larger molecules into smaller molecules for energy anabolism Using energy to build cell components, more complicated molecules Metabolism Balance between catabolism and anabolism Central biochemical pathways used for botΩ TCA cycle, glycolysis, pentose phosphate shunt Electron Transfer Major source of energy in cell Passage of electrons releases energy Requires electron donor and electron acceptor Electron transport found in all cells from bacteria to us Different donors, acceptors Electron energy can be stored Phosphorylation Energy Less energy than oxidation-reduction reactions that result in the electron transfer method, but still useful Useful energy level for most cell reactions No electron donor or acceptor needed Phosphate added via dehydration (removal of H2O) Released via hydrolysis (addition of H2O) ATP most common energy source GTP sometimes is present
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Me t ab olis m Sunlight Reduced geological compounds (rocks, inorganic compounds) (Reduced) biological macromolecules (starch, fats) (First energy source) (Major energy source today) (Energy source for animals) Energy CATABOLISM Phototrophy Lithotrophy Organotrophy ATP Short-term energy storage ANABOLISM Carbon, nitrogen, water Long-term energy storage Biosynthesis Catalysis and Enzymes Activation energy- energy required to bring all molecules in a chemical reaction into the reactive state (break bonds) Enzymes - catalytic proteins; speed up biochemical reaction rates by lowering activation energy Active site- portion of an enzyme to which substrate binds. Substrate product(s) aldolase enzyme: Fructose-1,6-bisphosphate glyceraldehyde-3- phosphate + dihydroxyacetone phosphate Very specific for their substrate Cellulose vs. starch example Enzymes can have small non-protein molecules that help in catalysis but aren’t part of the enzyme or the substrate. Two types: 1. Prosthetic groups - bound tightly to their enzyme, usually covalently and permanently Example- heme group in cytochromes 2. Coenzymes - loosely bound to their enzyme, may associate with different enzymes, usually derivatives of vitamins Example- NAD+, derivative of niacin Enzymes are named either for the substrate they bind or for the chemical reaction they catalyze with the addition of the suffix -ase For example, cellulase breaks down cellulose into glucose hydrolases break various chemical bonds with the addition of water Catabolism: The Microbial Buffet
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This note was uploaded on 10/11/2011 for the course BIOL 2051 taught by Professor Brininstool during the Spring '07 term at LSU.

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BIOL_2051_ch13_and_ch14_notes - Chapter 13 Energetics...

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