Download Enzymes

SI Bio6 Dr. Wright’s class
made by Pyeongsug Kim
Revised: 02/13/10
1. Why can pepsin(an enzyme) digest proteins not carbohydrate or lipid in stomach? How can pepsin be active in
stomach but not in mouth or small intestine?
An enzyme including pepsin reacts only with specific substrates. Stomach is acidic, the pH which pepsin has
optimum activity.
2. Match the term.
active site
the part of an enzyme that actually interacts with the reactants.
enzyme
Lowers the activation energy of a reaction.
Are biological catalysts that increase rate of chemical reactions by lowering energy
enzyme
required for a reaction to proceed.
enzyme
Reactions will not occur at a rate that supports survival without these
Series of reactions, each catalyzed by a different enzyme; The product of one
metabolic pathway
reaction is the substrate for the next.
Inborn error of metabolism
This is a genetic defect may lead to loss of function of that enzyme.
Are necessary for normal activity of enzymes; include metal ions such as Ca+2,
cofactor
Mg+2, Mn+2, Cu+2, and Zn+2 .
coenzyme
Are necessary for normal activity of enzymes ;are derived from vitamins; transport
small molecules needed by enzymes.
Inborn error of metabolism
In these situation, Intermediate will accumulate; this may lead to disease
a. active site
g. enzyme
b. cofactor
c. coenzyme
h. Inborn error of metabolism
f. metabolic pathway
3. Match the term.
End-product inhibition
Describes the process by which the end product of a pathway prevents further
activity along that pathway.
activation energy
An enzyme catalyzes a reaction by lowering this
Cu2+, Zn2+
This is an example of cofactor
NAD/FAD
are derived from vitamins and transfer hydrogens/electrons in the cell.
saturation
The point at which the reaction rate is highest.
Specificity
The property that an enzyme only reacts with a particular substate.
NAD/FAD
This is an example of coenzyme, which helps move electrons around.
a. NAD/FAD
b. Cu2+, Zn2+ c. saturation d. end-product inhibition
e. activation energy f. specificity
4. Answer the following question about enzyme inhibitors: competitive and allosteric inhibition.
a. Which type works by binding directly to the active site? Competitive
b. Which type works by binding outside the active site, but which distorts the active site when it binds o the
enzyme?.
Allersteric
c. In “end-product inhibition,” does the end product act is a competitive or allosteric inhibitor (indicate which one)?
allosteric inhibitor
e. Some poison or drugs bind to the enzyme's active site and reduces its activity. Which one? Competitive
5. What are two ways that “inborn errors of metabolism” can contribute to disease?
SI Bio6 Dr. Wright’s class
made by Pyeongsug Kim
1) End product of that pathway cannot be synthesized; may lead to disease
Revised: 02/13/10
2) Intermediate will accumulate; this may lead to disease
6. a. What is the name of the process that the end product of a pathway prevents further activity along that pathway?
Feedback inhibition
b. When is the process on(resumes)? In order word when is the pathway inhibited?
When end product of a pathway accumulates, it can then inhibit and enzyme that functions
earlier in the pathway to prevent more products.
c. When does the inhibition process stop? In other word when the pathway resumes?
When the end product is depleted, it is not available to inhibit the enzyme, so the
pathway resumes.
7. Match the term.
Catabolism
Anabolism
Oxidation
The type of reaction or process usually release energy (which can be recaptured by
the information of ATP)
The type of reaction usually require energy, which is stored in the newly-formed
chemical bonds.
Cu2+, Zn2+ is the form of this losing electrons
is the “currency” of energy in the cell. Energy is stored when ADP is converted to
ATP
this.
Reduction
Redox reaction
a. Catabolism
e. oxidation
Refers when an atom or molecule gains electrons. For example, becoming from
NAD+/FAD+ into NAD/FAD is this form
Refer to the coupled reactions when an atom or molecule gains or loses electrons.
b. Anabolism
c. Redox reactions (or Oxidation-reduction reactions)
f. Adenosine Triphosphate (ATP)
d. Reduction
7. Circle the answer.
a. In our body a chemical reaction rate affected by ( substrate concentrations/ enzyme concentrations/ both/
neither).
b. (Exergonic/ Endergonic) require input of energy to proceed.
(Exergonic/ Endergonic) release energy.
c. Endergonic products contain (more/less) free energy than reactants.
Exergonic products contain (more/less) free energy than reactants.
d. These reactions are (coupled / independent each other) in biologic systems..