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Transcript
Enzyme Activity Turnip Peroxidase Guaiacol AP Biology Tetraguaiacol Guaiacol Absorbance AP Biology Increases as reaction occurs Enzyme Activity Graph data What are you changing? Time (IV) What is the response? •Change in absorbance •(DV) How do you graph the data? •Absorbance vs time AP Biology Measuring Rates of Reaction Graph absorbance vs time Determine slope of increase AP Biology Enzyme Activity vs Temperature: Explain the graph. Where does denaturation fit into the graph? If another enzyme from a north sea crustacean was studied and its enzyme activity was plotted on the graph, where would it appear? If a hot springs bacterial enzyme was studied and its activity data was plotted, where would it lie? AP Biology Rxn Rate vs Enzyme Concentration Explain the graph. Why is the reaction rate linear and not curved? AP Biology Rxn Rate vs Substrate Concentration Explain the graph Why does it differ from the graph of Reaction Rate vs Enzyme Concentration When was the rate the highest, and why? When was the rate the slowest, and why? AP Biology Rate of Reaction Enzyme-Mediated Reaction: Moles of Product Produced vs Time. Which graph below-right summarizes the rate of the reaction depicted by the Moles of Product Produced vs Time graph? AP Biology Lock and Key model Simplistic model of enzyme action substrate fits into 3-D structure of enzyme’ active site H bonds between substrate & enzyme AP Biology like “key fits into lock” specificity In biology… Shape matters! Induced fit model More accurate model of enzyme action 3-D structure of enzyme fits substrate substrate binding cause enzyme to change shape leading to a tighter fit “conformational change” bring chemical groups in position to catalyze reaction AP Biology How does it work? Variety of mechanisms to: lower activation energy & speed up reaction synthesis active site orients substrates in correct position for reaction enzyme brings substrate closer together digestion active site binds substrate & puts stress on bonds that must be broken, making it easier to separate molecules AP Biology Factors Affecting Enzyme Fxn Enzyme concentration Substrate concentration Temperature pH Salinity Activators Inhibitors AP Biology catalase Factors affecting enzyme fxn: Enzyme Concentration Enzyme concentration as enzyme = reaction rate more enzymes = more frequently collide with substrate reaction rate levels off reaction rate substrate becomes limiting factor not all enzyme molecules can find substrate AP Biology enzyme concentration Factors affecting enzyme fxn: Substrate Concentration Substrate concentration as substrate = reaction rate more substrate = more frequently collide with enzyme reaction rate levels off reaction rate all enzymes have active site engaged enzyme is saturated maximum rate of reaction AP Biology substrate concentration Factors affecting enzyme fxn: Temperature Temperature Optimum T° greatest number of molecular collisions human enzymes = 35°- 40°C body temp = 37°C Heat: increase beyond optimum T° increased energy level of molecules disrupts bonds in enzyme & between enzyme & substrate H, ionic = weak bonds denaturation = lose 3D shape (3° structure) Cold: decrease T° molecules move slower decrease collisions between enzyme & substrate AP Biology Enzymes and temperature Different enzymes function in different organisms in different environments reaction rate human enzyme hot spring bacteria enzyme 37°C AP Biology temperature 70°C (158°F) Factors affecting enzyme fxn: SALINITY Salt concentration changes in salinity adds or removes cations (+) & anions (–) disrupts bonds, disrupts 3D shape disrupts attractions between charged amino acids affect 2° & 3° structure denatures protein enzymes intolerant of extreme salinity Dead Sea is called dead for a reason! AP Biology Factors affecting enzyme fxn: pH pH changes in pH adds or remove H+ disrupts bonds, disrupts 3D shape disrupts attractions between charged amino acids affect 2° & 3° structure denatures protein optimal pH? most human enzymes = pH 6-8 depends on localized conditions pepsin (stomach) = pH 2-3 trypsin (small intestines) = pH 8 0 1 2 3 4 5 6 7 8 9 10 11 AP Biology