Lecture_2 - Lecture 2 Bioenergetics High energy compounds...

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Lecture 2 Bioenergetics High energy compounds Susan C Evans, PhD
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Life requires an input of energy Bioenergetics – changes in energy during metabolic reactions Most energy is supplied by the sun Captured by plants, algae, and photosynthetic bacteria Used for synthesis of biological molecules Ingested by higher organisms (animals) Broken down to release energy used to synthesize biomolecules and macromolecules
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Cells obtain energy in two different ways: Chemotrophs – obtain energy by the oxidation of foodstuffs Phototrophs - obtain energy from the trapping of sunlight In both cases the energy is “stored” in the form of high energy compounds
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Energy flow Inorganic nutrients (CO 2 , H 2 O) Organic compounds Waste Macromolecules (CO 2 , H 2 O) Energy All organisms Photosynthetic organisms Light energy
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Thermodynamics System – matter within a defined region of space (such as a chemical reaction) Surroundings – matter present in the rest of the universe, outside the system
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1 st law of thermodynamics The total energy of the system and its surroundings is constant Energy can be changed from one form to another but it can never be created nor destroyed Energy released in the formation of chemical bonds must be used to Break other bonds Released as heat Stored as another form
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Entropy A measure of the degree of randomness or disorder in a system
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2 nd law of thermodynamics The total entropy (S) of a system plus that of its surroundings always increases Entropy may be decreased locally in the formation of an ordered structure only if it is increased in other parts of the universe by an equal or greater amount
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Gibbs free energy S surroundings = - H system /T S total = S system + S surroundings S total = S system H system /T -T S total = H system – T S system G = H system – T S system Total entropy will increase only if: S system > H system /T G = H system – T S system < 0 Total entropy change Gibbs free energy H is change in enthalpy
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This note was uploaded on 03/11/2009 for the course BIOS 342 taught by Professor Tanda during the Spring '09 term at Ohio University- Athens.

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Lecture_2 - Lecture 2 Bioenergetics High energy compounds...

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