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Enzymes
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Enzymes Enzymes: are proteins made of amino acids.Enzymes: are proteins made of amino acids. -Catalyst: they speed up chemical reactions & lower the activation energy. -Catalyst: they speed up chemical reactions & lower the activation energy. -Reusable: remain unchanged after the reaction -specific: there is a perfect enzyme for a certain substrate
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Are Enzymes reusable? Yes or NO
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Enzymes are….. A. A. Nucleic Acids B. B. Carbohydrates C. C. Proteins D. D. Lipids
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Enzymes 3D shape3D shape can be destroyed & denatured (change shape) with extreme changes in pH & temperaturecan be destroyed & denatured (change shape) with extreme changes in pH & temperature have active sites = places where substrate (food & waste) molecules attachhave active sites = places where substrate (food & waste) molecules attach
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Examples of Enzymes Catalase breaks down hydrogen peroxide (waste produced in cells) into water and oxygen 2H 2 O 2 ----> 2H 2 O + O 2 Lactase breaks down lactose in milk Lactase breaks down lactose in milk Protease breaks down proteins Protease breaks down proteins Lipase breaks down lipids Lipase breaks down lipids
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How Enzymes Work? Active sites on enzymes = places where a specific substrate bindsActive sites on enzymes = places where a specific substrate binds Enzyme-substrate complexes form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rateEnzyme-substrate complexes form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rate E+ S ES E + PE+ S ES E + P
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What are active sites?
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Two Model of Enzymes 1. lock & key model → substrate & the enzyme fit together perfectly 2. induced-fit model → enzymes change shape slightly to accommodate the substrate
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Lock & Key Model
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Induced-Fit Model
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Factors Affecting Enzyme Action Temperature – enzymes work best at certain temperatures Temperature – enzymes work best at certain temperatures (– 37 o C is best for human enzymes in the body) (– 37 o C is best for human enzymes in the body) pH – enzymes work best at certain pH; basic, neutral, and/or acidic environments pH – enzymes work best at certain pH; basic, neutral, and/or acidic environments ex.) Amylase in saliva at pH 7, ex.) Amylase in saliva at pH 7, Pepsin in the stomach at pH 2-3, Trypsin in the intestines at pH 9
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37° Temperature temperature reaction rate What’s happening here?! human enzymes
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7 pH pH reaction rate 20134568910 stomach pepsin intestines trypsin What’s happening here?! 11121314
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Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available. Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available. Coenzymes – helpers such as vitamins & minerals Coenzymes – helpers such as vitamins & minerals Other Factors Affecting Enzyme Action
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