10-11-17 Exam 2 Notes.docx - Chapter 6 Energy is the...

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Chapter 6Energy is the capacity to do work. States: Kinetic, energy of motion and Potential, stored energyHeat is most convenient way of measuring energy-1 calorie = heat req. to raise 1 g of water 1 degree CelsiusThermodynamics: chemistry concerned w/ energy changeCells are gov. by laws of physics and chemistryEnergy flows into the world from the sunPhotosynthetic organisms capture energyStore as potential energy in chem. BondsOxidation-Reduction or Redox: Oxidation-atom or molecule loses an electron; Reduction-atom or molecule gains an electron and higher level of energyOxidation-Reduction reactions-Redox are always paired1stlaw of thermodynamics: Energy cannot be created or destroyed, energy can only change from one form to another, total amount of energy in the universe remains constant, during each conversion some energy is lost as heat2ndlaw of thermodynamics: Entropy is cont. increasing, energy transformations proceed spontaneously to convert matter from a more ordered/less stable form to a less ordered/more stable formG = Energy available to do work, G = H – TSFree Energy = Enthalpy – Absolute Temp x EntropyHeat x Free Energy = change in free energyPositive Heat x G: Products have more free energy than reactants, H is higher or S is lover, not spontaneous requires input of energy, endergonicNegative Heat x G: Products have less free energy than reactants, H is lower or S is higher or Both, Spontaneous, Exergonic.Activation Energy: extra energy required to destabilize existing bonds and initiate a chemical reaction, exergonic reaction rate depends on the activation energy required (larger activation energy proceeds more slowly), Rate can be increase by heating which increases energy of reacting molecules or lowering activation energy, equilibrium exists between the relative amounts of reactants and productsATP: Adenosine Triphosphate, currency of cells, made of Ribose (5 C sugar), Adenine, Chain of 3 Phosphates (key to energy storage, bonds are unstable, ADP-2 P, AMP-1 P-lowest energy formATP Cycle: ATP Hydrolysis drives endergonic reactions, not suitable for long term energy (fats and carbohydrates are better) (cells store only a few seconds worth of ATP)ADP + P generates ATP + H2OCatalysts: Substances that influence chemical bonds to lower activation energy. Activation energy is used to destabilize chemical bonds, cannot violate laws of thermodynamics, do not alter proportion of reactant turnedinto productMost enzymes are protein (some are RNA)Shape of enzymes stabilizes a temporary association between substrates, no changed or consumed in reaction,carbonic anhydrase (200 mol of carbonic acid per hour made w/o enzyme, 600,000 mol formed per second w/ enzyme)Active Site of enzymes: Pockets or clefts for substrate binding, precise fitRate of enzyme-catalyzed reaction depends on concentrations of substrate and enzymeEnzymes can be suspended in cytoplasm or attached to cell membranes and organellesMultienzyme Complexes: subunits work together to form

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