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Enzymes. Catalysts of Life. Review of Chemical Reactions. A chemical reaction is a process that changes, or transforms, one set of chemicals into another Reactants are elements or compounds that enter into a chemical reaction
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Enzymes Catalysts of Life
Review of Chemical Reactions • A chemical reaction is a process that changes, or transforms, one set of chemicals into another • Reactants are elements or compounds that enter into a chemical reaction • Products are the elements or compounds produced by a chemical reaction • Chemical reactions usually require energy to get started • Activation energy is the energy that is needed to get a reaction started
What are enzymes? • Enzymes are proteins that hasten, or speed up, chemical reactions • A catalyst is a substance that speeds up the rate of a chemical reaction • Enzymes are biological catalysts • Enzymes speed up the reactions that take place in cells
How do enzymes work? • The molecule that an enzyme binds with or acts upon is called the substrate • The spot on an enzyme where the enzyme and substrate bind together is called the active site. • The active site is made of deep folds created by the folding of amino acid chains • Enzymes can be used over and over again after a reaction is complete
How do enzymes work? • Enzymes have a specific shape • Substrates also have a specific shape • In order for an enzyme and substrate to bind together and react, their shapes MUST fit together • This is called the lock-and-key model
How do enzymes work? • If an enzyme shape does not match with a substrate, there is no reaction • An enzyme’s shape can be changed if conditions are not right • If an enzyme’s shape is changed due to changing conditions, then the enzyme has been denatured • No reaction can occur if an enzyme’s shape is denatured • Factors that affect enzyme shape • pH – too acidic or too basic • Temperature – too hot or too cold • Enzyme concentration – how many enzymes are there?
How do enzymes work? • Web Link: • http://www.lew-port.com/10712041113402793/lib/10712041113402793/Animations/Enzyme_activity.html
Other factors affecting enzymes • Competitive inhibitors are molecules that are similar to the substrate’s shape • Competitive inhibitors get stuck in the active site and prevent the enzyme from binding with the substrate • Noncompetitive inhibitors are molecules that bind near, but not at, the active site • Noncompetitive inhibitors change the shape of the active site and prevent the enzyme from binding with the substrate
