aa - C hapter 8 An int roduction to Metabolism Organization...

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Chapter 8 – An introduction to Metabolism Organization of the Chemistry of Life into Metabolic Pathways A metabolic pathway begins with a specific molecule – altered in a series of defined steps each with a specific enzyme ending in a product Catabolic pathways – metabolic pathway that releases energy by breaking down complex molecules to simpler compounds o cellular repiration is a major catabolic pathway Anabolic pathways – consume energy to build complicated molecules from simpler ones o Called biosynthetic pathways also o E.g. synthesis of a protein Forms of energy The Laws of Energy Transformation First law of thermodynamics – conservation of energy o Energy can be transferred or transformed but not destroyed or created Second Law of thermodynamics – entropy o Every energy transfer or transformation increases entropy of the universe Spontaneous – a process that can occur without an input of energy o Does not imply that such process would occur quickly o Increases entropy Nonspontaneous – a process that can’t occur on its own o Decreases entropy Biological Order and Disorder Organisms are usually orderly in their cells making up large proteins with amino acids o But also makes disorder – takes in food, breaks it down etc Energy flows into the ecosystem as light and leaves as heat Free Energy Change of a reaction tells us whether it is spontaneous or nonspontaneous Gibbs free energy system – symbolized by the letter G o Free energy – portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. o Spontaneous – G must be negative o Nonspontaneous – G must be positive Free energy, stability, and Equilibrium
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Unstable systems have higher G’s and tend to change in such a way they become more stable (lower G) o Dye is less stable than spread randomly Al will move to greater stability Free energy increases when an object is pushed away from Equilibrium Free energy and metabolism Exergonic and endergonic reactions in Metabolism Exergonic – energy outward and proceeds with a net release of free energy – spontaneous Endergonic – absorbs free energy from surroundings and stores it in molecules o G is positive so they are nonspontaneous reactions. Equilibrium and Metabolism
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This note was uploaded on 10/07/2010 for the course HELLO IDK taught by Professor Armand during the Spring '10 term at Barber-Scotia.

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aa - C hapter 8 An int roduction to Metabolism Organization...

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