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XVII. Enzymes: Special proteins http://highered.mcgraw- hill.com/sites/0072495855/student_view0/ch apter2/animation__how_enzymes_work.htm l 2. http://bcs.whfreeman.com/thelifewire/conten t/chp06/0602001.html http://bcs.whfreeman.com/thelifewire/conten t/chp06/0602001.html
catalysts A. Function of enzymes: act as catalysts (which speed up chemical reactions) specific B. Enzymes are specific to the substrates on which they work.
C. Substrate—the reactant (substance) on which the enzyme works unchanged D. Enzymes remain completely unchanged by the reaction.
E. Factors affecting the rate at which an enzyme can work: 1. temperature 2. pH 3. concentration (of enzyme and of substrate) http://www.phschool.com/science/biology_ place/labbench/lab2/temp.html
Example: catalase It catalyzes the decomposition (break-down) of hydrogen peroxide into water and oxygen. 2H 2 O 2 2H 2 O + O 2 hydrogen peroxide water + oxygen
Additional notes on catalase: One molecule of catalase can break down 40 million molecules of hydrogen peroxide each second. Hydrogen peroxide is a harmful byproduct of certain cellular processes in organisms. Catalase is an enzyme that breaks down hydrogen peroxide. Cells make catalase in order to convert the hydrogen peroxide into harmless substances. Reference for last two slides: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enzymes.html (Found 9-15-08)http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enzymes.html
Example: carbonic anhydrase It is found in red blood cells where it catalyzes the reaction: CO 2 + H 2 O H 2 CO 3 carbon dioxide + water carbonic acid
Additional notes on the enzyme carbonic anhydrase: It enables red blood cells to transport carbon dioxide from the tissues to the lungs. One molecule of carbonic anhydrase can process one million molecules of CO 2 each second.