L5_BIOL1020_student-version220.pdf

L5_BIOL1020_student-version220.pdf - BIOL1020 Dr Jack Wang...

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BIOL1020 Dr. Jack Wang & Dr. Ulrike Kappler School of Chemistry and Molecular Biosciences Readings: Campbell’s Biology 10 th Ed: Ch8 (8.1-8.4), Ch9 (9.1), Ch10 (10.0-10.1) Lecture 5: Cellular energy
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Learning objectives for today’s lecture: 1. Explain how the laws of thermodynamics govern metabolic reactions 2. Explain how free energy changes in chemical reactions and relate these changes to metabolic processes 3. Define metabolism and relate this to transformations of energy and matter 4. Distinguish between anabolic processes and catabolic processes Keywords: Gibbs free energy, exergonic, endergonic, spontaneous and non-spontaneous reactions, coupled reactions 2
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Organisms continually transform energy through metabolic processes All energy transformations in nature are based on the same principles that will be explored in this lecture Figures 8.3 and 9.2 Energy and matter flow from one organism to another within the biosphere. Chemical energy Heat Energy 3
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Today’s topic…. Cellular energy conversions Sunlight Producers absorb light energy and transform it into chemical energy. Chemical energy in food is transferred from plants to consumers. Chemical energy (grass) Energy (definition: the capacity (of a system) to do work ) is constantly interconverted by living organisms: Chemical energy stored e.g. in the form of sugars can be converted into other forms of energy such a kinetic energy (e.g. movement) or heat 5
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What do people mean when they talk about potential energy ? This form of energy has the capacity to be released (but is not being released at the moment). A stone lying on top of a hill has a high potential energy (i.e. if it rolls down the slope of the hill this energy is released as kinetic energy through the motion of rolling) . Potential Energy 6
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When energy is used to do work, some energy is converted to thermal energy, which is lost as heat. An animal’s muscle cells convert chemical energy from food to kinetic energy, the energy of motion. A plant’s cells use chemical energy to do work such as growing new leaves. In living cells, chemical compounds store most of the energy as ‘potential energy’ 7
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Metabolism Is the totality of an organism s chemical reactions Arises from interactions between molecules Transforms matter and energy, subject to the laws of thermodynamics In living organisms energy conversions are linked to chemical reactions called metabolism * What are some cellular processes that require energy? * Do these create or destroy energy? * Do these create or destroy matter? 8
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First law of thermodynamics: The energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created and destroyed.
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