2–4 Chemical Reactions and Enzymes
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Transcript 2–4 Chemical Reactions and Enzymes
Chemical Reactions and
Enzymes
Why are enzymes important to
living things?
Standards
CLE 3210.1.3 – Describe how
enzymes regulate chemical reactions in
the body.
●Class Objectives:
Describe how the enzyme and
substrate interact to catalyze
chemical reactions.
Describe conditions that affect
enzyme function.
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Chemical Reactions
process that changes one set
of chemicals into another set
of chemicals
Chemical Reactions
always involve the breaking of
bonds in reactants and the
formation of new bonds in
products
reactants - elements or
compounds that enter into a
chemical reaction
products - elements or
compounds produced by a
chemical reaction
Energy in Reactions
Energy is released or
absorbed whenever chemical
bonds form or are broken.
Chemical reactions that
release energy often occur
spontaneously.
Energy may be released as
light, heat, and/or sound.
Energy in Reactions
Chemical reactions that
absorb energy will not occur
without a source of energy.
Every organism must have
a source of energy to carry
out chemical reactions
Activation Energy
energy that is needed to get a
reaction started
Enzymes
catalyst - substance that
speeds up the rate of a
chemical reaction
works by lowering a
reaction’s activation
energy
Enzymes
enzymes - proteins that act
as biological catalysts
very specific, generally
catalyzing only one chemical
reaction
part of an enzyme’s name is
usually derived from the
reaction it catalyzes
Enzyme Naming
The enzyme’s name is usually
from the chemicals in the reaction
it catalyzes.
Usually ends in -ase
Enzyme examples
DNA polymerase – links
nucleotides together to
make DNA
Carbonic anhydrase –
speeds up the conversion
of CO2 to carbonic acid in
the blood
The Enzyme-Substrate
Complex
Enzymes provide a site where
reactants can be brought
together to react.
Such a site reduces the
energy needed for reaction.
Substrates - reactants of
enzyme-catalyzed reactions
Enzyme-Substrate Complex(Lock
& Key Model)
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Substrate:
The reactant(s) of
the chemical
reaction.
●
Active Site:
Part of the
enzyme into
which the
substrate fits.
Induced Fit Model
Enzyme-substrate complex
Enzyme
how enzymes work…
hexokinase
Substrates
Glucose
ATP
Substrates bind to active
site on enzyme
lock and key
Once reaction is over,
products of reaction are
released and enzyme is
free to start process
again
Synthesis and Decomposition
Enzymes can participate in two
types of reactions:
Synthesis:
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A reaction in which two or more substrates are
combined to form one product.
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Decomposition:
A reaction in which one substrate is separated
to form two or more products.
Regulation of Enzyme
Activity
Enzymes can be affected by any
variable that influences a
chemical reaction
pH
temperature
certain proteins help turn
enzymes “on” or “off”