Chapter_08_Metabolism - Cell Metabolism Metabolism (from...

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Metabolism (from the Greek word metabole ,” which means change) is the totality of an organism’s chemical processes. Metabolic pathways (each step of which is catalyzed by an enzyme) are series of reactions that manage material and energy resources of the cell. There are two kinds: Catabolic pathways degrade or break down complex molecules to simpler compounds, to make energy stored in organic molecules available to do the cell’s work. An example is cell respiration, where glucose is broken down into CO 2 and H 2 O. Anabolic pathways consume energy to build complex molecules from simpler monomers. An example is the synthesis of proteins from amino acids. Bioenergetics is the study of how organisms use energy resources. Energy is the ability to do work. There are two kinds of energy: 1. Kinetic - energy of motion. 2. Potentia l - stored or possessed energy To use energy, chemical reactions must rearrange atoms of molecules in such a way that the potential energy stored in the molecules is converted to kinetic energy. There are two types of reactions: Exergonic , with a spontaneous net release (or decrease) of free energy ( G is negative), and Endergonic , which nonspontaneously absorbs free energy ( G is positive). In a reversible process, one direction is exergonic and the other is endergonic., and Energy coupling is the use of an exergonic process to power an endergonic one. Cell Metabolism A spontaneous process is a change that can occur without outside help and increases stability. Systems will most often change spontaneously if they move from a high energy and low entropy state to a l ow energy and high entropy state. In any spontaneous process, the free energy of a system decreases . Thermodynamics is the study of energy transformations that occur in a collection of matter. There are two Laws of Thermodynamics . 1.
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This note was uploaded on 04/01/2012 for the course BIO 141 taught by Professor Dr.cafferty during the Spring '11 term at Emory.

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Chapter_08_Metabolism - Cell Metabolism Metabolism (from...

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