biology chapter 8

biology chapter 8 - Chapter 8 An Introduction to Metabolism...

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Chapter 8: An Introduction to Metabolism Lecture 13: Reactions and Enzymes 8.1 A N O RGANISM S M ETABOLISM T RANSFORMS M ATTER AND E NERGY , S UBJECT TO THE L AW OF T HERMODYNAMICS - metabolism : totality of an organism’s chemical reactions *emergent property of life that arises from interactions between molecules within the orderly environment of the cell Organization of the Chemistry of Life into Metabolic Pathways - metabolic pathway : begins with a specific molecule, which is then altered in many steps resulting in a product…each step is catalyzed by an enzyme A—Enzyme1 B---Enzyme 2 C---Enzyme 3 D Start Rxn 1 Rxn 2 Rxn 3 Product - catabolic pathway : breakdown pathways; release energy by breaking down complex molecules to simpler compounds o major catabolic pathway: cellular respiration - anabolic pathway : consume energy to build complicated molecules from simpler ones * bioenergetics : study of how energy flows through living organisms Forms of Energy - energy : capacity to cause change; ability to rearrange a collection of matter - kinetic energy : relative motion of objects - heat / thermal energy : associated with the random movement of atoms or molecules - light : harnessed to perform work (powering photosynthesis in green plants - potential energy : energy that isn’t kinetic; matter posses because of its location/structure - chemical energy : refer to the potential energy available for release in a chemical reaction The Laws of Energy Transformation - thermodynamics : study of the energy transformations that occur in a collection of matter o system : denote the matter under study o surroundings : rest of the universe o isolated system : unable to exchange either energy or matter with its surroundings o open system : energy and matter can be transferred between the system and its surroundings organisms are open systems - First Law of Thermodynamics : the energy of the universe is constant; energy cannot be created or destroyed o also known as the principle of conservation of energy - Second Law of Thermodynamics : every energy transfer increases the entropy of the universe o Loss of usable energy during energy transfer is that each such event makes the universe more disordered o Entropy : a measure or disorder, or randomness o For a process to occur on its own without outside help (an input of energy) it must increase the entropy of the universe
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Spontaneous: a process that can occur without an input of energy o for a process to occur spontaneously, it must increase the entropy of the universe - Biological Order and Disorder : o living systems increase the entropy of their surroundings o yet, cells create ordered structures from less organized starting materials… however, an organism also takes in organized forms of matter and energy from the surroundings and replaces them with less ordered forms ie: animal obtains starch from food…catabolic pathways break these molecules down…releases small molecules that possess less chemical
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