2.4 Chemical Reactions and Enzymes Everything that happens in an organism is based on chemical...
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Transcript of 2.4 Chemical Reactions and Enzymes Everything that happens in an organism is based on chemical...
![Page 1: 2.4 Chemical Reactions and Enzymes Everything that happens in an organism is based on chemical reactions.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649f315503460f94c4cf0e/html5/thumbnails/1.jpg)
2.4 Chemical Reactions and Enzymes
Everything that happens in an organism is based on chemical
reactions
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Chemical reactions
• A chemical reaction is a process that changes, or transforms, one set of chemicals into another
• The elements or compounds that enter into a chemical reaction are known as reactants
• The elements or compounds produced by a chemical reaction are known as products
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Baking soda + vinegar chemical reaction
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Chemical reactions
• Chemical reactions always involve changes in the chemical bonds that join atoms in compounds
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Energy in reactions
• Energy is released or absorbed whenever chemical bonds form or are broken. Because chemical reactions involve breaking and forming bonds, they involve changes in energy.
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Energy changes
• Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.
• An example of an energy releasing reaction is hydrogen gas burning, or reacting, with oxygen to produce water vapor.
• 2H + O ₂ ₂ 2H O₂
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Hindenberg
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Energy changes
![Page 9: 2.4 Chemical Reactions and Enzymes Everything that happens in an organism is based on chemical reactions.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649f315503460f94c4cf0e/html5/thumbnails/9.jpg)
Energy changes
![Page 10: 2.4 Chemical Reactions and Enzymes Everything that happens in an organism is based on chemical reactions.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649f315503460f94c4cf0e/html5/thumbnails/10.jpg)
Energy changes
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Activation energy
• Even chemical reactions that release energy do not always occur spontaneously. If they did, the paper you are writing on might burst into flames.
• Chemists call the energy that is needed to get a reaction started the activation energy.
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Activation energy
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Enzymes
• A catalyst is a substance that speeds up the rate of a chemical reaction. Catalysts work by lowering a reaction’s activation energy.
• Enzymes are proteins that act as biological catalysts. Enzymes speed up chemical reactions that take place in cells.
• Enzymes work by lowering the activation energies.
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Enzyme action
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Enzyme action
• For a chemical reaction to take place, the reactants must collide with enough energy so that existing bonds will be broken and new bonds will be formed.
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The Enzyme-Substrate Complex
• Enzymes provide a site where reactants can be brought together to react. Such a site reduces the energy needed for reaction
• The reactants of enzyme-catalyzed reactions are known as substrates
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The Enzyme-Substrate Complex
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Regulation of Enzyme Activity
• Many enzymes are affected by changes in temperature. Enzymes produced by human cells generally work best at temperatures around 37℃, the normal temperature of the human body.
• Enzymes also work best at certain pH values and solute concentrations
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Regulation of enzyme activity
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Regulation of enzyme activity