2. B.7.1 Describe the characteristics of
• Enzymes are protein molecules that act as catalysts for
biological reactions.
• The enzymes are highly specific for each reaction and are
very efficient.
• The enzymes are highly specific because of their tertiary
and quaternary structures.
• The active site is the part of the enzyme that reacts with
the substrate.
3. B.7.2 Compare inorganic catalysts and
Biological Catalysts both types of catalysts Inorganic Catalysts
They are specific to the The catalysts provide an They are not specific to
reaction. alternative path for the the reaction.
reaction with a lower
They are proteins, like They increase the rate of They can be anything.
activation energy.
amino acids. the reaction.
They are specific to They can be applied to
human bodies and life. other situations.
4. B.7.3 Describe the relationship between
substrate concentration and enzyme activity.
• As the concentration of the substrate increases the rate of
the reaction increases, when the concentration is low there
are enough active sites but the rate of reaction is lower.
• Higher concentrations have a higher rate of reaction, but
when the rate reaches a certain point (Vmax) it peaks. At
this point all of the active sites are used and the rate
cannot be increased any more.
5. B.7.4 Determine Vmax and the value of the Michaelis constant (km)
by graphical means and explain its significance.
Vmax is impossible to attain in an enzyme reaction so we use half of vmax
to characterize a specific enzyme reaction. To determine vmax you find the
point at which the graph is parallel to the x-axis. To determine the Michaelis
constant divide vmax by two and find that y-value on the graph, the
corresponding x value is the Michaelis constant. The Michaelis constant
and half of vmax help to identify an enzyme reaction and to determine what
concentration of the substrate should be used to get the desired
concentration.
6. B.7.5 Describe the mechanism of enzyme action, including
enzyme substrate complex, active site and induced fit model.
The active site is the part of the enzyme that reacts with the substrate. It
is formed by the tertiary or quaternary structure of the enzyme. The
active site on the enzyme is a groove that can change its shape to fit the
substrate.
7. B.7.6 – Compare competitive inhibition
• Inhibitors: substances that slow down the rate of enzyme-
catalyzed reactions
• Competitive Inhibitors:
• Have a similar structure to the substrate and occupy the active site
on the enzyme
• Increasing the substrate concentration will lessen the effect of the
competitive inhibitors
• Vmax of the reaction does not change, but Km increases.
8. •Non-competitive Inhibitors:
• Bind to the enzyme but not at the active site
• Causes the enzyme to change its shape so that the substrate
cannot bind to the enzyme
• Increasing the substrate concentration will not change the effect
of non-competitive inhibitors
• Vmax but Km will stay the same.
•The effects of both inhibitors are reversible.
9. B.7.7 – State and explain the effects of heavy metal ions,
• Metal Ions:
• Can poison enzymes by reacting with -SH groups replacing the
hydrogen atom with a heavy metal atom or ion so that the
tertiary structure is altered.
• Temperature:
• Increasing the temperature will increase the rate of enzyme-
catalyzed reactions to a certain point. Enzymes have an optimal
temperature where they will work best. After this point, the
enzymes denature.
• pH:
• At the enzymes, optimal pH, the reaction will occur fastest with
the enzyme present. However, at different pH levels, the
charges on the amino acid residues change, affecting the
bonds between them. The enzyme denatures.
