BB lecture 10-15 'free' energy

BB lecture 10-15 'free' energy - Chapter 8 (pp.141-150)...

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Chapter 8 (pp.141-150) Energy, reactions and thermodynamic laws Learning objectives: • Distinguish between kinetic and potential energy • Explain the first and second laws of thermodynamics in your own words • Explain the role of catabolic and anabolic pathways in cellular metabolism • Distinguish between exergonic and endergonic reactions in terms of free energy change • Be able to explain the relationship of free energy to stability, work capacity, and spontaneous change • Understand how cellular ‘work’ is powered by ATP, and how ATP is regenerated
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Energy comes in two forms: Kinetic and Potential Kinetic energy is the energy of motion Potential energy is stored energy Potential energy may be stored in the position of a molecule with respect to its concentration gradient In chemical bonds, potential energy is stored in the position of the electrons that form the bond A key feature of all forms of energy is the ability of potential energy to become kinetic energy and vice versa. The conversion of energy from one form to another is never 100% efficient, a certain amount is lost to the environment, usually as “heat”.
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The Laws of Energy Transformation Thermodynamics is the study of energy transformations A closed system, such as that approximated by liquid in a thermos, is isolated from its surroundings In an open system , energy and matter can be transferred between the system and its surroundings Organisms are open systems
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The First Law of Thermodynamics According to the first law of thermodynamics, the energy of the universe is constant Energy can be transferred and transformed Energy cannot be created or destroyed The first law is also called the principle of conservation of energy
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The Second Law of Thermodynamics During every energy transfer or transformation, some energy is unusable, often lost as heat According to the second law of thermodynamics, every energy transfer or transformation increases the entropy (disorder) of the universe
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[the first law of thermodynamics: there is no creation or destruction of matter-energy] A closed system: no sand enters the glass and none leaves… none is created, none is destroyed Sand in the top chamber (low entropy) is capable of doing work by falling, Sand in the bottom chamber (high entropy) has spent its capacity to do work . [the second law, entropy always Increases] Although the quantity of sand in the hour glass is constant, its qualitative distribution is constantly changing: the bottom chamber is filling up and the top chamber becoming empty.
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Living cells… experience a constant flow of materials in and out, preventing metabolic pathways from reaching equilibrium Figure 8.7 (b) An open system: Flowing water keeps driving the generator because intake and outflow of water keep the system
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BB lecture 10-15 'free' energy - Chapter 8 (pp.141-150)...

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