lecture 7 biao ding

lecture 7 biao ding - Biol 113 AU2010 Lecture 7 Metabolism...

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1 Biol 113 AU2010 Lecture 7 Metabolism A. An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics B. The laws of energy transformation C. ATP powers cellular work by coupling exergonic reactions to endergonic reactions D. Enzymes speed up metabolic reactions by lowering energy barriers A. An Organism’s Metabolism Transforms Matter and Energy, Subject to the Laws of Thermodynamics Metabolism is the totality of an organism’s chemical reactions Metabolism is an emergent property of life that arises from interactions between molecules within the cell The living cell is a miniature chemical factory where thousands of reactions take place The cell extracts energy and applies energy to perform work Some organisms even convert energy to light, as in bioluminescence Metabolism Organization of the Chemistry of Life into Metabolic Pathways A metabolic pathway begins with a specific molecule and ends with a product Each step is catalyzed by a specific enzyme Enzyme 1 Enzyme 2 Enzyme 3 D C B A Reaction 1 Reaction 3 Reaction 2 Starting molecule Product Catabolic pathways release energy by breaking down complex molecules into simpler compounds Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism Anabolic pathways consume energy to build complex molecules from simpler ones The synthesis of protein from amino acids is an example of anabolism Bioenergetics is the study of how organisms manage their energy resources A condensation reaction or more specifically a dehydration reaction occurs when two monomers bond together through the loss of a water molecule Enzymes are macromolecules that speed up the dehydration process Polymers are disassembled to monomers by hydrolysis , a reaction that is essentially the reverse of the dehydration reaction The Synthesis and Breakdown of Polymers Fig. 5-2 Short polymer HO 1 2 3 H HO H Unlinked monomer Dehydration removes a water molecule, forming a new bond HO H 2 O H 1 2 3 4 Longer polymer (a) Dehydration reaction in the synthesis of a polymer HO 1 2 3 4 H H 2 O Hydrolysis adds a water molecule, breaking a bond HO H H HO 1 2 3 (b) Hydrolysis of a polymer Forms of Energy Energy is the capacity to cause change Energy exists in various forms, some of which can perform work Potential energy is energy that matter possesses because of its location or structure Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules Kinetic energy is energy associated with motion Chemical energy is potential energy available for release in a chemical reaction Energy can be converted from one form to another Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential
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This note was uploaded on 11/29/2010 for the course BIO 113 taught by Professor Swenson during the Fall '08 term at Ohio State.

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lecture 7 biao ding - Biol 113 AU2010 Lecture 7 Metabolism...

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