Bios 208 1st Edition Lecture 12 Outline of Last Lecture I. DNA and Proteins as Tape Measures of Evolution II. MetabolismIII. Forward Reaction and Reverse ReactionIV. Thermodynamic LawsV. Kinetic and Potential EnergyVI. Free-Energy ChangeVII. Units of EnergyVIII. Order as a Characteristic of LifeOutline of Current Lecture I. Energy changes in exergonic and endergonic reactionsII. Equilibrium and MetabolismIII. The Structure and Hydrolysis of ATPCurrent LectureI. Energy changes in exergonic and endergonic reactionsA. Free energy (G) is E that is available to do work. We’re interested in G, the change in G between the reactants and products. B. If G is negative (< 0), the reaction releases E and is exergonic.C. If G is positive (> 0), the reaction requires E and is endergonic.II. Equilibrium and MetabolismA. Reactions in a closed system eventually reach equilibrium and then do no work. B. Cells are not in equilibrium; they are open systems experiencing a constant flow of materials. C. A defining feature of life is that metabolism is never at equilibrium. D. A catabolic pathway in a cell releases free energy in a series of reactions.E. Closed and open hydroelectric systems can serve as analogies.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.III. The Structure and Hydrolysis of ATPA. ATP (adenosine triphosphate) is the cell’s energy shuttleB. ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groupsC. ATP powers cellular work by coupling exergonic reactions to endergonic reactions •D. A cell does three main kinds of work a) Chemical b) Transport c) Mechanical E. To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one F. Most energy coupling in cells is mediated by ATPG. The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis H. Energy is released from ATP when the terminal phosphate bond is broken I. This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselvesJ. The three types of cellular work (mechanical, transport, and chemical) are powered by the hydrolysis of ATPK. In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reactionL. Overall, the coupled reactions are
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