Lecture 9 - BIOL104 Principles of Biology I September 13,...

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BIOL104 Principles of Biology I September 13, 2010 Lecture #9
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Energy can take many forms • Kinetic energy – Energy of motion • Potential energy – Stored energy – Stored in the form of covalent bonds – Photosynthesis converts energy from the sun into covalent bonds in sugar molecules
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Energy in covalent bonds • It takes 98.8 kcal to break one mole of C-H bonds in organic molecules • Molecules with LOTS of C-H bonds store LOTS of energy • Fat molecules have many C-H bonds
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1st Law of Thermodynamics Energy can not be created or destroyed It can only change from one form to another Total amount of energy of the universe remains constant Energy flows through the biological world in one direction
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2nd Law of Thermodynamics Disorder of the universe is continuously increasing Disorder = entropy
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Chemical reactions can be predicted based on changes in free energy • Chemical bonding reduces disorder • Heat increases disorder • Free energy – The amount of energy actually available to break and then form other chemical bonds – The energy available to do work in any system
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Gibbs’ Free Energy The energy available to do work in any system G = Gibbs’ free energy (limits the system to the cell) G = H - TS H = energy contained in a molecules chemical bonds (enthalpy) S = energy unavailable because of disorder (entropy) T = temperature (°K)
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Chemical reactions form new ones in the products • So, reactions can produce changes in free energy
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This note was uploaded on 05/03/2011 for the course BIOL 104 taught by Professor Bray-speth during the Fall '11 term at Saint Louis.

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Lecture 9 - BIOL104 Principles of Biology I September 13,...

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