CH 6 Outline

CH 6 Outline - 0 Energy Flow in the Life of a Cell Chapter...

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Energy Flow in the Life of a Cell Chapter 6 0
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Free Radicals Unbound molecular fragments with the wrong number of electrons Example O2^-1 (should be O2^-2) Highly Reactive Can disrupt structure of molecules “age spots” as you get older is example 0
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These Keep Free Radicals in Check Superoxide dismutase Catalase
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Superoxide Dismutase Catalyzes the formation of hydrogen peroxide from oxygen free radicals and hydrogen ions Accumulation of hydrogen peroxide can be lethal to cells O2^- + 2H^+ -- H2O2
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Catalase Catalyzes the formation of oxygen and water from hydrogen peroxide 2H2O2 ----- 2H2O + O2
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Overall effect… O2^- +H^+ H2O2 H20 +o2 Red molecules = Free radicals = Superoxide dismutase action Pink molecules = Toxic to cells = Catalase action
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Roundworm Experiments Diet supplemented with superoxide dismutase and catalase increased life span of normal worms Diet also allowed worms genetically engineered for susceptibility to free radicals to live normal life span
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What Is Energy? Energy: Capacity to do work 2 different forms of energy 1. Potential energy (“stored energy”) chemical energy in bonds, electrical charge in a battery, rock at the top of a hill 2. Kinetic Energy (“energy of movement”) Light, heat, electricity, moving objects
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What Can Cells Do with Energy? Energy inputs become coupled to energy-requiring processes Cells use energy for: Chemical work Mechanical work Electrochemical work The Laws of Thermodynamics describe the basic properties of Energy
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First Law of Thermodynamics The total amount of energy in the universe remains constant unless energy is added or removed from the system Energy can undergo conversions from one form to another, but it “ cannot be created or destroyed
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One-Way Flow of Energy The sun is life’s primary energy source Producers trap energy from the sun and convert it into chemical bond energy All organisms use the energy stored in the bonds of organic compounds to do work (i.e. the 3 phosphate molecules in ATP can be cleaved off to release Energy)
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Second Law of Thermodynamics Energy conversion is never 100 percent efficient The total amount of energy is flowing from “ high-energy forms to low-energy forms
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Measure of degree of disorder in a system The living world can resist the flow toward maximum entropy (max. disorder) only because it is re-supplied
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CH 6 Outline - 0 Energy Flow in the Life of a Cell Chapter...

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