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Ch. 8 notes

Ch. 8 notes - Ch 8 04:44 Metabolism the totality of an...

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Ch. 8 04:44 Metabolism – the totality of an organism’s chemical reactions Metabolic pathway – begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. Each step is catalyzed by a specific enzyme Catabolic pathway – “downhill,” metabolic pathways that release energy by breaking down complex molecules to simpler compounds Cellular respiration – glucose and other organic fuels are broken down in the presence of oxygen to carry carbon dioxide and water energy stored in those organic molecules becomes available to do work Anabolic pathways – a.k.a. “biosynthetic pathways,” “uphill,” consume energy to build complicated molecules from simpler ones Ex) synthesis of amino acid from simpler molecules Bioenergetics: the study of how energy flows through living organisms Energy – capacity to cause change/ability to rearrange a collection of matter Kinetic energy – energy associated with the relative motion of objects Heat/thermal energy – kinetic energy associated with the random movement of atoms or molecules Light – energy that can also be harnessed to perform work (photosynthesis) Potential energy – energy that matter possesses because of its location/structure Chemical energy – potential energy available for release in a chemical reaction In organisms – comes from light! Thermodynamics – the study of energy transformations that occur in a collection of matter System = matter being studied Surroundings = everything outside the system Open system – energy and matter can be transferred between the system and the surroundings 2 laws First law of thermodynamics
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energy can be transferred and transformed, but it cannot be created or destroyed = principle of the conservation of energy Second law of thermodynamics Every energy transfer or transformation increases the entropy of the universe (measure of disorder/randomness) Heat is released = loss of usable energy during energy transfer/transformation Spontaneous process – a process that can occur without an input of energy For a process to occur spontaneously, it must increase the entropy of the universe Free-energy change, G -1878, J. Willard Gibbs Gibbs free energy of a system = G portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system G = H - T S change in system’s enthalpy – (temp in K)(change in system’s entropy) only processes with a negative G are spontaneous H is negative T S is positive Both: H - T S = - G G is positive or 0 = nonspontaneous
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Ch. 8 notes - Ch 8 04:44 Metabolism the totality of an...

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