ProblemWhat kind of roles the factors of pH levels and temperature have on various reaction rates. What roles inhibitors and activations play on enzymatic reactions.

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John Sciullo



AP Lab 2 Enzyme Catalysis

Abstract:                AP Lab Enzymes, introduced us to the catalyzing proteins called, enzymes, focusing on the effects that various variables have on enzyme reaction rate.  To further our knowledge of enzymes, we used a variety of chemicals to stimulate different conditions.  Using sulfuric acid (H2SO4) we were able to stimulate an acidic environment.  By boiling water in one part of the experiment, we were able to see the effects of temperature on reaction rate.  Overall we tested a wide array of variables, investigating their effects on reaction rate.  At the end of the experiment we were able to come up with the following viable conclusion; the variables that had the most significant impact on reaction rate had to do with changes in pH levels of the solutions, and the temperature.

                Splitting off into groups we began the lab by observing a reaction in which catalase was placed into a solution, releasing bubbles of O2.  This reaction introduced us to enzymes and their activities.  Shortly after, we began investigating the effects various variables had on the reaction rate.  In demonstrating the effect of boiling on enzymatic activity, we were able to learn that sharply increasing the temperature of the enzymatic solution, the reaction rate lowered.  As a group, we inferred that the high temperatures caused the enzymes, proteins, to unravel and denature.  We came to the same conclusion upon testing the effects of pH.

                The last sections of the lab called upon us to investigate the differences between the uncatalysed rate of H2O2 decomposition and the enzyme-catalyzed rate of H2O2 decomposition.  Investigating the uncatalyzed rate of decomposition, an individual was picked from the group to come in the following day and test the effect of leaving the H2O2 in room temperature for 24 hours.  By comparing the results between the two, we were better able to understand the effects enzymes play in reactions.  

Emphasis:         Data Analysis and Collection

Objectives:        Before doing this lab you should understand:

  • the general functions and activities of enzymes;
  • the relationship between the structure and function of enzymes;
  • the concept of initial reaction rates of enzymes;
  • how the concept of free energy relates to enzyme activity;
  • that changes in temperature, pH, enzyme concentration and substrate concentration can affect the initial reaction rates of enzyme-catalyzed reactions; and
  • catalyst, catalysis, and catalase

After doing this lab you should be able to:

  • measure the effects of changes in temperature, pH, enzyme concentration, and substrate concentration on reaction rates of an enzyme-catalyzed reaction in a controlled experiment; and
  • Explain how environmental factors affect the rate of enzyme-catalyzed reactions.

Problem:                What kind of roles the factors of pH levels and temperature have on various reaction rates.  What roles inhibitors and activations play on enzymatic reactions.

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  • Enzymes are proteins produced by living cells; they act as catalysts in biochemical reactions.  A catalyst affects the rate of a chemical reaction.  One consequence of enzyme activity is that cells can carry out complex chemical activities at relatively low temperatures.
  • In an enzyme-catalyzed reaction, the substance to be acted upon, the substrate, binds reversibly to the active site of the enzyme.
  • The active site is the portion of the enzyme that interacts with the substrate, so that any substance that blocks or changes the shape of the active site affects activity of that enzyme. ...

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