Notes: Chemical Reactions and Enzymes A Chemical Reaction is a process that changes one set of chemicals into another set of chemicals. The compounds that enter into a chemical reaction are known as reactants The compounds that are made by the reaction are the products Chemical reactions always involve the breaking bonds in the reactants and forming new bonds in the products. Below is an example that we will refer to quite often this semester. C6H12O6 + 6 O2  6 CO2 + 6 H2O + ATP reactants products

In order to stay alive, living things need to carry out chemical reactions that require energy. Activation Energy is the amount of energy needed to get a chemical reaction started.

A catalyst is something that allows a reaction to occur more quickly by lowering the amount of energy needed. (i.e. lowering the activation energy).

Enzymes are special proteins that act as catalysts Enzymes are special proteins that act as catalysts. Enzymes speed up chemical reactions that take place inside cells (some enzymes break things down, other enzymes build things).

Substrate: substance that the enzyme acts on or changes. Active Site: The part of the enzyme that attaches to the substrate. Most enzymes will only work on 1 specific substrate (like a lock that will only be opened by the right key).

Other Important Things to Know: Enzymes can do their job over and over again, as long as they have something to work on (enzymes don’t get used up). Just like living things have an optimal range of conditions they can work in, so does an enzyme. Changes in pH and temperature can make the shape of an enzyme change and therefore make the enzyme work less efficiently or not work at all (becomes denatured).