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Chapter 6. Ground Rules of Metabolism. Energy. Energy = capacity to do work Potential Energy—stored energy in resting object Kinetic Energy—energy of motion. Thermodynamics. 1 st Law of Thermodynamics: Energy cannot be created or destroyed Converted from one form to another
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Chapter 6 Ground Rules of Metabolism
Energy • Energy = capacity to do work • Potential Energy—stored energy in resting object • Kinetic Energy—energy of motion
Thermodynamics • 1st Law of Thermodynamics: Energy cannot be created or destroyed • Converted from one form to another • 2nd Law of Thermodynamics: Energy flows from organized to disorganized forms • Concentrated energy tends to disperse spontaneously • Moves from useable to non-useable energy • Chemical bonds resist this direction of energy flow
thermodynamics • Entropy: Measure of randomness or disorder in a system • Organized energy = useable = less entropy • Disorganized = not useable = more entropy • Living things must maintain ongoing replacement of lost energy
metabolism • All chemical reactions within a cell or organism • Reactants • Products • +=
Chemical reactions • Anabolic • Building reactions (dehydration synthesis) • Endergonic—need energy • A + B + Energy = C • Usually not spontaneous • Catabolic • Breaking down reactions (hydrolysis) • Exergonic—release energy • C = A + B + Energy • Usually spontaneous
Chemical Reactions • Activation Energy—minimum energy that can get a reaction to run on it’s own. • Cells control energy input into reactions, therefore controlling timing & speed of reactions.
Chemical reactions • Endergonic coupled with exergonic • Released energy from one fuels other C = A +B + Energy D + E + Energy = F
ATP • Energy source for cells • Created by photosynthesis or in mitochondria
ATP • Breaking down ATP releases energy • This powers cell fuctions • E.g. Active transport proteins
ENzymes • Biological catalysts • Speed up chemical reactions • Don’t start reactions on their own • Reusable • Can catalyze in forward & reverse • Very specific!
enzymes • Lowers activation energy • Makes reactions faster & easier
Controls over enzymes • Concentration • Enzymes • Reactants • Products • Temperature • pH • Enzyme cofactors • vitamins
Controls over enzymes • Inhibition • Competitive—binds to site first or more strongly • Non-competitive—binds to different area, changing enzyme bonding area
Controls over enzymes • Feedback inhibition • Product of reaction binds to allosteric site • Shuts down reaction