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LAB 5: Enzymes

LAB 5: Enzymes. TCTC Biology 101 Lab Rinehart. Enzyme Function. Enzymes - specialized proteins that function as catalysts for metabolic reactions

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LAB 5: Enzymes

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  1. LAB 5: Enzymes TCTC Biology 101 Lab Rinehart

  2. Enzyme Function • Enzymes - specialized proteins that function as catalysts for metabolic reactions • As catalysts, Enzymes lower the EA (Activation Energy) of reactions in the cell (they lower the amount of energy required for a reaction to start!) • Energy is not added to the reaction, the amount required to start the reaction is decreased • The enzyme is not used up in the process!

  3. Enzyme Function and EA

  4. Enzyme Naming • Each enzyme is specific to a certain reaction and a certain substrate or substrate set • They are named for their substate (e.g. catechol v. catecholase for today’s lab, lactose v. lactase)

  5. Enzyme Structure

  6. Induced Fit Model

  7. Optimal Enzyme Function • Optimal Enzyme function requires enzyme-specific chemical environments • pH • Temperature • Altering this environment can cause the enzyme to change shape or break apart (denature) and eliminating its catalytic function

  8. Catalysts and Concentration • As you increase the concentration of enzyme or substrate, you increase the incidence of an enzyme “hooking up” with its substrate and hence increase the rate of reaction. • Note that some enzymes can actually inhibit their own rate of reaction (if the substrate can’t leave the active site of the enzyme)

  9. Catechol and Catecholase • Present in most fruits and vegetables • Catechol reacts with oxygen  benzoquinone • pigment that causes “bruises” • Catecholase is the enzyme that acts as catalyst for this reaction. • When cells uninjured, catechol and oxygen are separate. Damage cells = reaction

  10. Lab Hypotheses A Exercise A: “pH effects on Catecholase activity” Ho: There is no effect of the pH of the environment on the activity of catecholase. Ha: The pH of the environment affects the activity of catecholase.

  11. Lab Hypotheses B Exercise B: “effect of enzyme concentration on catecholase activity” Ho: There is no effect of enzyme concentration on catecholase activity. Ha: Enzyme concentration affects catecholase activity

  12. Experimental Directions • Follow the lab directions VERY CAREFULLY (if it says WAIT then WAIT!!) • Remember, the catechol is the substrate and it is in your box. The catecholase, the enzyme, comes from the potato juice. Don’t leave here not understanding how and why you made blanks. • We will discuss the results from all 5 sections next week and distribute results for use in report on web

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