BIOL-L112 Exam 3 with precise detailed 5 5 5 5 5 5
answers
What is the definition of an enzyme? - Correct answer ✔macromolecule that
5 5 5 5 5 5 5 5 5 5 5 5
acts as a catalyst, which speeds up reactions without being consumed by the
5 5 5 5 5 5 5 5 5 5 5 5 5
reaction
What is the activation energy of a reaction? - Correct answer ✔amount of
5 5 5 5 5 5 5 5 5 5 5 5 5
energy that reactants must absorb before a chemical reaction will start
5 5 5 5 5 5 5 5 5 5
how does an enzyme alter the activation energy of a reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5 5
answer ✔decreases the Ea 5 5 5
do enzymes affect the Delta G of a metabolic reaction? - Correct answer ✔no
5 5 5 5 5 5 5 5 5 5 5 5 5
what are substrates? - Correct answer ✔substrates are the reactants that
5 5 5 5 5 5 5 5 5 5 5
enzymes act on 5 5
what part of an enzyme binds its substrate? - Correct answer ✔active site
5 5 5 5 5 5 5 5 5 5 5 5
what types of bonds help hold the substrate to the enzyme? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5 5 5
✔weak bonds such as hydrogen, ionic, and hydrophobic interactions
5 5 5 5 5 5 5 5
,what is induced fit and how does it alter the catalytic activity of an enzyme? -
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔When the substrate forms weak bonds with R groups of AAs
5 5 5 5 5 5 5 5 5 5 5 5
5in the active site, a slight change in the conformation of the enzyme will
5 5 5 5 5 5 5 5 5 5 5 5 5 5
occur allowing the substrate to bind more tightly to the active site. The
5 5 5 5 5 5 5 5 5 5 5 5 5
interactions between the substrate the key AAs in the active site will increase
5 5 5 5 5 5 5 5 5 5 5 5 5
the catalytic ability of the enzyme.
5 5 5 5 5
why are concentrations of enzymes within cells usually quite low? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔The concentration of enzymes is low in cells because an enzyme can
5 5 5 5 5 5 5 5 5 5 5 5
5be used over and over again to catalyze a specific metabolic reaction. Once
5 5 5 5 5 5 5 5 5 5 5 5 5
the products are formed, they leave the active site of the enzyme and new
5 5 5 5 5 5 5 5 5 5 5 5 5 5
reactants can bind to the active site. 5 5 5 5 5 5
Give two examples of mechanisms that take place within the active site of an
5 5 5 5 5 5 5 5 5 5 5 5 5 5
enzyme that function to lower the activation energy of a reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5 5
answer ✔1. active site provides a template for substrate orientation 2. active
5 5 5 5 5 5 5 5 5 5 5 5
site can participate directly in catalytic reaction by forming a brief covalent
5 5 5 5 5 5 5 5 5 5 5 5
bond with substrate 5 5
when do enzymes become saturated in a metabolic reaction? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5
✔when all active sites are filled with substrates
5 5 5 5 5 5 5
if you added more reactants, would the reaction rate increase when an
5 5 5 5 5 5 5 5 5 5 5 5
enzyme is saturated? - Correct answer ✔once an enzyme is saturated, the only
5 5 5 5 5 5 5 5 5 5 5 5
5way to increase the reaction rate is to increase the amount of enzyme.
5 5 5 5 5 5 5 5 5 5 5 5
,why is important for an enzyme to function under optimal conditions? -
5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔allow enzyme to achieve a shape where it functions at its
5 5 5 5 5 5 5 5 5 5 5 5 5
highest rate 5
what are cofactors of enzymes? - Correct answer ✔non-protein molecules that
5 5 5 5 5 5 5 5 5 5
some enzymes require for catalytic activity
5 5 5 5 5 5
inorganic cofactor? - Correct answer ✔magnesium
5 5 5 5 5
organic cofactor? - Correct answer ✔vitamin; coenzyme
5 5 5 5 5 5
what type of chemical bond will irreversibly inhibit an enzyme? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔covalent 5
what type of chemical bond will reversibly inhibit an enzyme? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔weak bonds or interactions
5 5 5 5
in terms of reversible inhibition, what is the difference between a competitive
5 5 5 5 5 5 5 5 5 5 5 5
and a noncompetitive enzyme inhibitor? - Correct answer ✔Competitive
5 5 5 5 5 5 5 5 5
inhibitors bind to the active site of an enzyme and block the substrate from
5 5 5 5 5 5 5 5 5 5 5 5 5 5
binding. Noncompetitive inhibitors bind to an allosteric site (site other than
5 5 5 5 5 5 5 5 5 5 5
the active site) on the enzyme. This binding alters the shape of the active site
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
and decreases the enzyme's ability to bind its substrate.
5 5 5 5 5 5 5 5
, what types of molecules are used within the body to generate energy? -
5 5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔monosaccharides, fatty acids, glycerol, and amino acids.
5 5 5 5 5 5 5 5 5
oxidized to generate CO2 and water
5 5 5 5 5
why does glucose have more potential energy than CO2? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5
✔Glucose has more chemical bonds that can be rearranged through chemical
5 5 5 5 5 5 5 5 5 5 5
reactions. The rearrangement of some of these bonds releases energy - thus
5 5 5 5 5 5 5 5 5 5 5 5
the bonds in glucose contain much more potential energy. CO2 does not have
5 5 5 5 5 5 5 5 5 5 5 5 5
chemical bonds that can be easily rearranged and thus it has very little
5 5 5 5 5 5 5 5 5 5 5 5 5
potential energy. 5
is the oxidation of glucose an endergonic or exergonic reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔exergonic because the change in free energy is negative.
5 5 5 5 5 5 5 5 5
How is the energy that is generated through the oxidation of glucose use in
5 5 5 5 5 5 5 5 5 5 5 5 5 5
the cell? - Correct answer ✔About 34% of the energy is used to generate ATP.
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
The rest is released as heat. Heat can be use for thermoregulation or
5 5 5 5 5 5 5 5 5 5 5 5 5
dissipated from the body through sweat. 5 5 5 5 5
what happens when electrons are relocated between molecules? - Correct
5 5 5 5 5 5 5 5 5 5
answer ✔energy is released
5 5 5
what are oxidation-reduction reactions? - Correct answer ✔reactions that
5 5 5 5 5 5 5 5 5
involve the partial or complete transfer of one or more electron from one
5 5 5 5 5 5 5 5 5 5 5 5 5
reactant to another 5 5
answers
What is the definition of an enzyme? - Correct answer ✔macromolecule that
5 5 5 5 5 5 5 5 5 5 5 5
acts as a catalyst, which speeds up reactions without being consumed by the
5 5 5 5 5 5 5 5 5 5 5 5 5
reaction
What is the activation energy of a reaction? - Correct answer ✔amount of
5 5 5 5 5 5 5 5 5 5 5 5 5
energy that reactants must absorb before a chemical reaction will start
5 5 5 5 5 5 5 5 5 5
how does an enzyme alter the activation energy of a reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5 5
answer ✔decreases the Ea 5 5 5
do enzymes affect the Delta G of a metabolic reaction? - Correct answer ✔no
5 5 5 5 5 5 5 5 5 5 5 5 5
what are substrates? - Correct answer ✔substrates are the reactants that
5 5 5 5 5 5 5 5 5 5 5
enzymes act on 5 5
what part of an enzyme binds its substrate? - Correct answer ✔active site
5 5 5 5 5 5 5 5 5 5 5 5
what types of bonds help hold the substrate to the enzyme? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5 5 5
✔weak bonds such as hydrogen, ionic, and hydrophobic interactions
5 5 5 5 5 5 5 5
,what is induced fit and how does it alter the catalytic activity of an enzyme? -
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔When the substrate forms weak bonds with R groups of AAs
5 5 5 5 5 5 5 5 5 5 5 5
5in the active site, a slight change in the conformation of the enzyme will
5 5 5 5 5 5 5 5 5 5 5 5 5 5
occur allowing the substrate to bind more tightly to the active site. The
5 5 5 5 5 5 5 5 5 5 5 5 5
interactions between the substrate the key AAs in the active site will increase
5 5 5 5 5 5 5 5 5 5 5 5 5
the catalytic ability of the enzyme.
5 5 5 5 5
why are concentrations of enzymes within cells usually quite low? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔The concentration of enzymes is low in cells because an enzyme can
5 5 5 5 5 5 5 5 5 5 5 5
5be used over and over again to catalyze a specific metabolic reaction. Once
5 5 5 5 5 5 5 5 5 5 5 5 5
the products are formed, they leave the active site of the enzyme and new
5 5 5 5 5 5 5 5 5 5 5 5 5 5
reactants can bind to the active site. 5 5 5 5 5 5
Give two examples of mechanisms that take place within the active site of an
5 5 5 5 5 5 5 5 5 5 5 5 5 5
enzyme that function to lower the activation energy of a reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5 5
answer ✔1. active site provides a template for substrate orientation 2. active
5 5 5 5 5 5 5 5 5 5 5 5
site can participate directly in catalytic reaction by forming a brief covalent
5 5 5 5 5 5 5 5 5 5 5 5
bond with substrate 5 5
when do enzymes become saturated in a metabolic reaction? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5
✔when all active sites are filled with substrates
5 5 5 5 5 5 5
if you added more reactants, would the reaction rate increase when an
5 5 5 5 5 5 5 5 5 5 5 5
enzyme is saturated? - Correct answer ✔once an enzyme is saturated, the only
5 5 5 5 5 5 5 5 5 5 5 5
5way to increase the reaction rate is to increase the amount of enzyme.
5 5 5 5 5 5 5 5 5 5 5 5
,why is important for an enzyme to function under optimal conditions? -
5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔allow enzyme to achieve a shape where it functions at its
5 5 5 5 5 5 5 5 5 5 5 5 5
highest rate 5
what are cofactors of enzymes? - Correct answer ✔non-protein molecules that
5 5 5 5 5 5 5 5 5 5
some enzymes require for catalytic activity
5 5 5 5 5 5
inorganic cofactor? - Correct answer ✔magnesium
5 5 5 5 5
organic cofactor? - Correct answer ✔vitamin; coenzyme
5 5 5 5 5 5
what type of chemical bond will irreversibly inhibit an enzyme? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔covalent 5
what type of chemical bond will reversibly inhibit an enzyme? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔weak bonds or interactions
5 5 5 5
in terms of reversible inhibition, what is the difference between a competitive
5 5 5 5 5 5 5 5 5 5 5 5
and a noncompetitive enzyme inhibitor? - Correct answer ✔Competitive
5 5 5 5 5 5 5 5 5
inhibitors bind to the active site of an enzyme and block the substrate from
5 5 5 5 5 5 5 5 5 5 5 5 5 5
binding. Noncompetitive inhibitors bind to an allosteric site (site other than
5 5 5 5 5 5 5 5 5 5 5
the active site) on the enzyme. This binding alters the shape of the active site
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
and decreases the enzyme's ability to bind its substrate.
5 5 5 5 5 5 5 5
, what types of molecules are used within the body to generate energy? -
5 5 5 5 5 5 5 5 5 5 5 5 5
Correct answer ✔monosaccharides, fatty acids, glycerol, and amino acids.
5 5 5 5 5 5 5 5 5
oxidized to generate CO2 and water
5 5 5 5 5
why does glucose have more potential energy than CO2? - Correct answer
5 5 5 5 5 5 5 5 5 5 5 5
✔Glucose has more chemical bonds that can be rearranged through chemical
5 5 5 5 5 5 5 5 5 5 5
reactions. The rearrangement of some of these bonds releases energy - thus
5 5 5 5 5 5 5 5 5 5 5 5
the bonds in glucose contain much more potential energy. CO2 does not have
5 5 5 5 5 5 5 5 5 5 5 5 5
chemical bonds that can be easily rearranged and thus it has very little
5 5 5 5 5 5 5 5 5 5 5 5 5
potential energy. 5
is the oxidation of glucose an endergonic or exergonic reaction? - Correct
5 5 5 5 5 5 5 5 5 5 5 5
answer ✔exergonic because the change in free energy is negative.
5 5 5 5 5 5 5 5 5
How is the energy that is generated through the oxidation of glucose use in
5 5 5 5 5 5 5 5 5 5 5 5 5 5
the cell? - Correct answer ✔About 34% of the energy is used to generate ATP.
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
The rest is released as heat. Heat can be use for thermoregulation or
5 5 5 5 5 5 5 5 5 5 5 5 5
dissipated from the body through sweat. 5 5 5 5 5
what happens when electrons are relocated between molecules? - Correct
5 5 5 5 5 5 5 5 5 5
answer ✔energy is released
5 5 5
what are oxidation-reduction reactions? - Correct answer ✔reactions that
5 5 5 5 5 5 5 5 5
involve the partial or complete transfer of one or more electron from one
5 5 5 5 5 5 5 5 5 5 5 5 5
reactant to another 5 5
