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Chemical Reactions and Enzymes
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Are processes that change or transform, one set of chemicals into another. Drive all the activities associated with life.
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Involve reactants (starting materials) and products (ending materials). The atoms of the reactants are rearranged to form the products.
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There are two types Endothermic ▪ Absorb energy ▪ Breakdown macromolecules Exothermic ▪ Release energy ▪ Build macromolecules
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Need some energy to get started The needed energy is called activation energy. ▪ Activation energy is a chemical push Is required for both exothermic and endothermic reactions. Is lowered by enzymes ▪ Enzymes are biological catalysts that speed up chemical reactions, but are not used up by them.
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Why do enzymes speed up reactions? Enzymes speed up reactions by lowering the activation energy (E a ) of a reaction. The activation energy is the energy needed to start a reaction. Different reactions have different activation energies. reaction (time) energy (kJ) E a with enzyme E a without enzyme
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Are large folded proteins that are made of hundreds of amino acids.
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All enzymes have active sites Active sites ▪ Form in the protein folds. ▪ Have a complimentary substrate shape.
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Speed up chemical reactions by binding with specific molecules. The specific molecule is a substrate. Promote specific chemical reactions
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http://www.youtube.com/watch?v=V4OPO6J QLOE
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Are affected by heat, acidity, and enzyme concentration Enzymes function with in a certain temperature range. Enzymes cease to function if the strength of acids in body fluids is too high or too low. Enzyme concentration determines if a reaction occurs.
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Enzymes and temperature
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Work with a partner to answer questions 1-3 of Assessment 2.4 on page 53 of your Biology textbook. Write the questions and answers in your notebook. Answer the questions thoughtfully and with complete sentences.
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Enzymes and temperature
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