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Chapter 3: Enzyme Notes
What is a chemical reaction?
A chemical reaction is a process that changes / transforms one set of chemicals into another. Chemical
reactions involve changes in chemical bonds that join atoms in compounds.
Reactants are elements or compounds that enter into a chemical reaction.
Products are elements or compounds that are produced by chemical reactions.
Activation Energy – The energy needed
Endergonic
Exergonic
Energy that is absorbed
Energy that is released
Which graph is endergonic and which one is exergonic?
Endergonic
Exergonic
Enzymes
Enzymes are natural catalysts made from proteins. Enzymes speed up reactions taking place within
cells by lowering activation energy. Enzymes contain a site where reactions are brought together to
react. Reactions for enzyme-catalyzed reactions are called substrates. Substrates bind to a site on
enzymes called the active site. Active sites and substrates have complimentary shapes – they fit
together like a lock and key.
What factors can influence enzymes?
Enzymes can be affected by any variable that influences chemical reactions, such as temperature
(they work best at temperatures similar to the human body) and pH. When out of the ideal ranges
for temperature and/or pH, enzymes begin to breakdown or become inactive. This is called
denature.
Extra Notes:
Mass and energy are conserved during chemical transformation. So, beginning mass is equal to
ending mass and beginning energy is equal to ending energy.
Because of energy conservation, organisms need a source of energy (food, light, etc.) for reactions
to occur.