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Life 6 7 - Life Ch 6-7 Chapter 6 Energy Enzymes and...

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Life Ch. 6-7 Chapter 6: Energy, Enzymes and Metabolism I. Physical principles that underlie biological energy transformations -energy is the capacity to do work. Work is what occurs when a force operates on an object over a distance. Energy is also known as the capacity for change. Energy is transformed A. Two types of energy and metabolism Two basic types of energy: 1. Potential: energy of state or position-stored energy. Stored in chemical bonds, concentration gradient or electric charge imbalance. 2. Kinetic: energy of movement. Does work -metabolism: sum total of all reactions. Types: 1. Anabolic: links simple molecules to form more complex ones. Creates energy. 2. Catabolic: breaks down complex molecules into simple ones and releases the energy stored in chemical bonds. B. First Law of thermodynamics: Energy is neither created nor destroyed C. Second law of thermodynamics: Disorder tends to increase When energy is converted some of that energy becomes unavailable to do work. Some energy is lost with disorder. i. Not all energy can be used. Total energy=usable energy+unusable energy -enthalpy(H)-total energy. Usable energy is free energy(G). Free energy is required for all chemical reactions of cell activities. Entropy is S, measuring disorder multiplied by absolute temperature. So H=G+TS, interested in usable energy so G=H-TS. -If ∆G is negative, free energy is released. If ∆G is positive, free energy is required (consumed). Without free energy a rxn doesn’t occur -∆H: total amount of energy added to the system (greater than 0), or released (H<0) -∆S: also depends on T to affect G. + means more disorder. – means less disorder. ii. disorder tends to increase -the second law predicts that as a result of energy transformations, disorder tends to increase. D. Chemical reactions release or consume energy Anabolic reactions increase complexity (order) while catabolic reactions break down complexity (create disorder). -Catabolic reactions may break down an ordered reactant, releasing free energy (-G), so are exergonic reactions. Complex free energy+small molecules -anabolic reactions: consume free energy (+G), endergonic. Free energy+small molecules complex mc -chemical equilibrium: balance between forward and reverse reactions. Delta G=0 E. Chemical equilibrium and free energy are related Not all reactions go to completion. Each has a specific equilibrium point, which is related to the free energy released by reaction under specified conditions. A large positive delta G means the reaction goes all to the right, but if the product is present, such a reaction runs backward. A delta G near zero is characteristic of a readily reversible reaction. II. What is the role of ATP in biochemical energetic ATP is useful in that it releases a relatively large amount of energy when hydrolyzed, and it can phosphorylate many different molecules.
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