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2-4 Chemical Reactions
& Enzymes
Chemical Reactions
• Changes or transforms one
set of chemicals to another
• The chemicals you start
with are called the
reactants
• The compounds or
elements made by the
reaction are the products
Energy in Reactions
• The amount of energy
needed to start a
reaction: activation
energy
Catalyst
• A catalyst is a
substance that
speeds a chemical
reaction.
• Catalyst work by
lowering reaction’s
activation energy.
Enzymes
• Enzymes are proteins that act as biological catalysts.
• Cells use enzymes to speed up chemical reactions that take place in cells.
• Enzyme speed up reactions by lowering the activation energies.
• An enzyme will only catalyze (speed up) one reaction, therefor there are thousands of different enzymes
Note:
Enzymes
end in
ase Catalase
Amalase
Enzymes
• A place where
substrates come
together to react
• Reduces the energy
needed for a reaction
to occur.
All enzymes have an active site,
where substrates are attracted to.
• Enzymes are used over and over again.
Substrate
• The substance
changed or acted
upon by an enzyme is
the substrate.
The Enzyme Substrate complex
• Enzyme and substrate fit together like a puzzle.
• The active site shape matches the substrates shape.
• The substrate and active site meet and change the shape of the active site causing a reaction and a product is made
Which one will fit ?
• Enzymes are specific
to one type of
reaction!!!
The factors that affect enzyme
activity are
• pH
• Temperature
• Amount of substrate
Affects of temperature on an
enzyme
• If temp too high or too
low the enzyme will
not fit. No reaction
will occur.
How pH affects an enzyme
• If the pH is too high or
low the enzyme will
not work, because its
shape will change.
pH
• Optimal pH.
• pH too low or too high, the enzyme changes shape
• No reaction
Analyze the graph at what ph does
Chymotrypsin function best?
Temperature
• Optimal Temperature
• Enzymes and substrates move quicker and connect more often.
• If the temp is too high the enzyme will be destroyed.
What is the optimal temp for this
enzyme
Amount Of Substrate Present
• Not enough: less reaction
• More substrate= more reaction.
• This continues until the enzymes are saturated.