Chemical Reactions and
Enzymes
September 2011
Chemical Reactions
• A process that changes, or transforms one set
of chemicals into another
Reactant (+ Reactants)  Product or Products
Reactants on the left Products on the right
CO2+H2O H2CO3
H2CO3CO2+H2O
Chemical reactions always involve changes in
chemical bonds.
Energy in Reactions
• Chemical reactions that release
energy often occur spontaneously.
• Chemical reactions that absorb
energy will not occur without a
source of energy.
Activation Energy
Enzymes
• Enzymes act as
catalysts
• A catalyst is a
substance that speeds
up the rate of a
chemical reaction.
• Enzymes speed up
chemical reactions that
take place in cells.
Enzymes
Enzyme Action
• Enzymes are very specific, catalyzing only one
reaction.
• Their name is derived from the reaction it
catalyzes.
• Enzymes provide a site where reactants can be
brought together to react.
• This reduces energy needed for reaction
• The reactants of enzyme-catalyzed reactions are
known as substrates
• enzymes in action
Assignment
Answer p. 53 1-5
Complete Analyzing Data p. 51 1-6