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Unformatted text preview: Chapter 8: An Introduction to Metabolism Concept: An organism’s metabolism transforms matter and energy, subject to laws of thermodynamics All energy we consume comes from the sun in the form of heat. In may multicellular organisms, many cells export chemical products that are used in other parts of the organism (cellular respiration) and this drives the cellular economy by extracting the energy stored in sugars and other fuels. Cells use this energy to perform various types of work, such as transporting solutes across the plasma membrane. • Organization of the Chemistry of Life into Metabolic Pathways o Metabolism : totality of an organism’s chemical reactions; an emergent property of life that arises from interactions between molecules within the orderly environment of the cell. o Metabolic pathway : series of chemical reactions that occur in a cell; this begins with a specific molecule, which is then altered in a series of defined steps—resulting in a certain product. • Catabolic processes: release energy---breakdown pathways . • Break food down into energy and raw materials proteins amino acids}use these to make own proteins. • Anabolic processes: consume energy—biosynthetic pathways (put things together). • Forms of Energy o Energy is the capacity to do work (kinetic energy vs. potential energy) o Kinetic energy : energy associated with the relative motion of other objects. o Heat (thermal energy) : kinetic energy associated with the random movement of atoms or molecules o Potential energy : energy that matter possesses because of its location or structure • When chemical reactions take place, potential energy is converted to kinetic energy (energy cannot be created nor destroyed but can be converted from one form into another) o Chemical energy : potential energy available for release in a chemical reaction. o Free energy : portion of a system’s energy that can perform work when the temperature and pressure are uniform. • The Laws of Energy Transformation ( thermodynamics-science of energy transmission) o The First Law of Thermodynamics • Energy in the universe is constant; Any non-nuclear process can change energy from one form to another (Energy can be transferred and transformed, but it cannot be created or destroyed)----energy can be stored. • Cheetah can convert the chemical energy of the organic molecules in its food to kinetic and other forms of energy. o The Second Law of Thermodynamics • Every energy transfer or transformation increases the entropy of the universe. • Things in nature are disordered; entropy is a measure of this disorder. • The entropy of a system may decrease as long as the total entropy of the universe increases....
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This note was uploaded on 04/30/2008 for the course BIO 123 taught by Professor Cusic during the Spring '08 term at University of Alabama at Birmingham.
- Spring '08