Enzyme Catalysis Assignment | Buy assignments online
BIOL 102: Lab 6
Enzyme Catalysis
PRE-LAB ASSIGNMENT:
Students are expected to read pages 1 to 4 before coming to the lab to complete the experiments.
Print this entire lab packet and bring it to the laboratory.
Please provide a FULL lab report for this experiment following the “Lab Report Guidelines”.
Objectives:
Observe the reaction of catalase and hydrogen peroxide
Demonstrate the effects of extreme temperatures on catalase activity
Learn how to establish a baseline for the amount of peroxide in a 1.5% solution.
Use titration techniques to determine the rate of hydrogen peroxide decomposition by enzyme catalysis
Investigate spontaneous decomposition of hydrogen peroxide to oxygen and water.
Background:
Enzyme Structure and Function
Thousands of different kinds of chemical reactions take place in a living cell, and nearly all of them are
mediated by enzymes. Enzymes are biomolecules that speed up chemical reactions. Without the action of
enzymes, metabolic reactions would be extremely slow.
For example, if you recall from an earlier unit that carbohydrates are a major source of energy for all cells.
They exist in several classes: monosaccharides are simple sugars; disaccharides are composed of two
monosaccharides; polysaccharides are made up of three or more monosaccharides. Organisms take in the
various carbohydrates as nutrients. Eventually the molecules would break down into monosaccharides on
their own, but not in time to support a cell’s life. Therefore, cells utilize enzymes to speed up the process.
Enzyme-Substrate Kinetics
Enzymes are catalysts, chemicals that speed up chemical reactions without itself being changed in the course
of the reaction. Most enzymes are highly specific in their action, catalyzing only one type of chemical reaction
or, at most, a small number of very similar reactions. The specific reactants that bind to a particular enzyme
are called substrates. Substrates bind to the enzyme at the active site. Active sites only allow selective
substrates to bind to it and are responsible for the enzyme-substrate specificity. When the enzyme is reacting
with the substrate, a complex is formed.
The figure to the left illustrates the specificity of the substrate to the
enzyme and the enzyme-substrate complex that is formed after they bind.
Note that in the picture, the arrows go in both directions. This illustrates
the principle of reversibility, meaning that an enzyme can break down
substrates, as well as put the substrates back together.
In some enzymes, the shape of it is not exactly complementary to the shape of the substrate. The binding of
the substrate causes a conformational change that induces a tighter and more accurate fit for itself within the
active site and stabilizes the interaction between enzyme and substrate. This is called the “induced fit model.”
Did you know?
There are over 2,000 known enzymes and each one is involved in a specific chemical reaction.
