Lecture 11-12 BlkBd

# Lecture 11-12 BlkBd - Different forms of energy Energy can...

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Unformatted text preview: Different forms of energy Energy can take a number of different forms. These depend on the stability and complexity of the system being considered. Heat is the energy resulting from random molecular movement. Temperature is the measurement of that energy. Heat is the end-of-the line form of energy because it is generated by the random movement of simple molecules and atoms. Heat is often the end point of metabolic processes. Potential (or stored) energy- capacity to do work. The energy within the chemical bonds of a molecule is potential energy. Kinetic energy - the energy contained within a moving object. Heat is the kinetic energy of randomly moving molecules. Energy Energy transformation. Potential energy can be converted into kinetic energy. Entropy- a measure of the degree of disorder in a system. The organization of matter tends towards an increasing degree of disorder unless energy is expended to keep entropy low. The second law of thermodynamics states that: Every time there is energy transfer or transformation there is an increase in the overall entropy of the universe. There is an increasing tendency towards disorder within the universe. Energy Free energy . The amount of energy in a system that is available to do work. At any given temperature free energy is the difference between the total energy of a system and the degree of entropy it has. An unstable system (i.e. has a low degree of entropy) has a greater amount of free energy. Free energy of a system: [G] = its total energy [H] - (the temperature x its entropy [TS]) As a chemical process proceeds, the change in free energy is represented as: ∆G = ∆H - T ∆S Whether the change in G is positive or negative determines whether a reaction releases energy or requires energy. Energy Endergonic and Exergonic reactions. A negative (-ve) ∆G means that the system has given up free energy. Energy is released to do work. This is an Exergonic reaction. Energy is released and can be used to make something happen within the cell. A positive (+ve) ∆G means that the system has gained free energy. Energy is absorbed. This is an Endergonic reaction. Energy must be added into the process to make it happen. How the cell organizes and manages these two types of reaction are the basis of cellular metabolism....
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## This note was uploaded on 02/28/2012 for the course BIO 220 taught by Professor Morre during the Spring '09 term at USC.

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Lecture 11-12 BlkBd - Different forms of energy Energy can...

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