Unit 3 Notes

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University of California - Irvine
Biological Sciences
Diane O' Dowd

An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics  Metabolism- the totality of an organism’s chemical reactions Organization of the Chemistry of Life into Metabolic Pathways  Metabolic pathway- begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product o Each step catalyzed by a specific enzyme  Catabolic pathways- pathways that release energy by breaking down complex molecules into simpler compounds o Cellular respiration: sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water  Anabolic pathways- consume energy to build complicated molecules from simpler ones o “biosynthetic pathways” o Synthesis of an amino acid from simpler molecules  Bioenergetics- the study of how energy flows through living organisms Forms of Energy  Energy- capacity to cause change o Kinetic energy- energy associated with the relative motion of objects o Heat/thermal energy- kinetic energy associated with the random movement of atoms or molecules o Potential energy- not kinetic; energy because of its location or structure o Chemical energy- the potential energy available for release in a chemical reaction The Laws of Energy Transformation  Thermodynamics- the study of the energy transformations that occur in a collection of matter  First law of thermodynamics- energy can be transferred and transformed, but it cannot be created or destroyed o Principle of conservation of energy  Second law of thermodynamics- o Entropy- measure of disorder, or randomness o Second law- every energy transfer or transformation increases the entropy of the universe o Spontaneous process- a process that can occur without an input of energy  For a process to occur on its own, it must increase the entropy of the universe  Biological order and disorder o Depletion of chemical energy is accounted for by heat generated during metabolism Free-Energy Change, ΔG  free energy- the portion of a system’s energy that can perform work when temperature and pre
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