1.3 enzymes Flashcards
activation energy
the
energy required to
initiate a chemical
reaction
catalyst
a substance
that speeds up the
rate of a chemical
reaction by lowering
the activation energy
for the reaction; is
not consumed in the
reaction
enzyme
a biological
macromolecule that
catalyzes, or speeds up,
chemical reactions in
biological systems
active site
e the site on
an enzyme where the
substrate binds; where
the chemical reaction
that is catalyzed by the
enzyme takes place
what shape do Most enzymes have
globular shapes
substrate
a reactant
that interacts with the
enzyme in an enzymecatalyzed reaction
enzyme-substrate
complex
the
combined structure
of an enzyme with a
substrate that is bound
to the enzyme’s active
site
induced fit
the change in shape of the active site to
accommodate the substrate is called induced fit.
coenzymes
Organic molecules that assist an enzyme
cofactors
Some enzymes require the presence of metal ions, such as iron or zinc,
what can affect the activity of an enzyme
Temperature and pH are two important factors that can cause this
alteration.
what sort of Ph level do pepsin acts best in
in the acidic environment of the stomach, its
optimum pH
Inhibitors
a molecule
that binds to the
allosteric or active
site of an enzyme and
causes a decrease in
the activity of that
enzyme
competitive inhibition
Competitive inhibitors
interact with the active site of the enzyme. When both the substrate and an inhibitor are
present, the two compete to occupy the active site. When the inhibitor is present in high
enough concentration, it will out-compete the substrate for the active site. !is blocks the
substrate from binding, and the reaction that the enzyme normally catalyzes does not occur.( simply put the inhibitor in the active site fights to keep the substrate away)
non-competitive inhibition
Non-competitive inhibitors bind to an allosteric
site on an enzyme. !is causes the conformation of the enzyme to change in such a way
as to reduce its ability to interact with the substrate at its active site. As a result, there is
a decrease in the activity of the enzyme.
allosteric site
a site
on an enzyme that
is not the active site,
where other molecules
can interact with and
regulate the activity of
the enzyme
activator
a molecule
that binds to the
allosteric site of an
enzyme and keeps
an enzyme active or
causes an increase
in the activity of that
enzyme
feedback inhibition
the product of one reaction acts as a
substrate for the enzyme that catalyzes the next reaction in the pathway. A common way
that biochemical pathways are regulated is by a process called feedback inhibition. In
feedback inhibition, the product of the last reaction of the pathway is a non-competitive
inhibitor of the enzyme that catalyzes a reaction at the beginning of the pathway. !is
form of regulation is a way that the cell has for ensuring that products of a pathway are
not produced unnecessarily. When enough product is available, its synthesis and all the
reactions related to its synthesis are turned o# or reduced. ( simpler: Biochemical pathways are like assembly lines in the body, where each step produces a product used in the next step. In feedback inhibition, the product of the last reaction acts as a signal to regulate the pathway. When this final product accumulates, it acts like a brake, inhibiting the enzyme responsible for the initial step of the pathway. This slowdown prevents unnecessary production when enough product is available, conserving energy and resources.
