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Enzymes Chapter 2: Section 2.5 Objectives • SWBAT explain the effect of a catalyst on activation energy. • SWBAT describe how enzymes regulate chemical reactions and maintain homeostasis. Starter: How can this be possible Catalyst • A catalyst lowers activation energy. • Catalysts are substances that speed up chemical reactions. – decrease activation energy – increase reaction rate – speed up reactions. Enzymes are catalysts in living things • Enzymes allow chemical reactions to occur under tightly controlled conditions. – Like inside of a cell or intercellular space. • Enzymes are catalysts in living things. – Enzymes are needed for almost all processes. – Enzymes are almost always proteins. Detailed Definition Enzymes • UC Davis Site: http://chemwiki.ucdavis.edu/Biological_Chem istry/Catalysts • When we think about information and its reliability, the source is important. If you would like to read in detail about enzymes (at a college level) check out this website. Point of Review • • • • • • Enzymes are proteins. Proteins are what kind of Molecule? Answer: a carbon-based molecule. Proteins are made up of what? Answer: they are made up of amino acids. Proteins are polymers of amino acids (making amino acids monomers). Reactions with and without enzyme Substrate refers to your reactants Enzymes function in a small range of conditions • Disruptions in homeostasis can prevent enzymes from functioning. – Enzymes function best in a small range of conditions (remember importance of water’s special properties – water is a buffer). – Changes in temperature and pH can break hydrogen bonds (remember, organisms have a very narrow range of temperatures, pH and other conditions in which they can survive). An enzyme’s function depends on its structure. • An enzyme’s structure allows only certain reactants to bind to the enzyme. substrates (reactants) – substrates – active site enzyme Substrates bind to an enzyme at certain places called active sites. An enzyme’s function depends on its structure. • The lock-and-key model helps illustrate how enzymes function. – substrates brought together – bonds in substrates weakened Substrates bind to an enzyme at certain places called active sites. The enzyme brings substrates together and weakens their bonds. The catalyzed reaction forms a product that is released from the enzyme. Examples of Enzymes • Amylase – made by salivary glands and pancreas (facilitates the breaking down of starch and glycogen into glucose). • Amino acid tryptophan is the substrate for the synthesis of serotonin. – Serotonin is a steroid that is a neurotransmitter (a chemical substance that transmits nerve impulses across synapses). – Involved in mood, appetite, sleep, memory, learning and depression (upping levels tends to relieve depression).