=Enzymes= '''Enzymes are ''protein catalysts'' that speed up the chemical reactions necessary for life''' [image:http://i.imgur.com/jsRk1gw.jpg?4] Enzymes are a type of protein. Proteins are made out of a long chain of amino acids (a group of small chemical molecules). The amino acid chain is a folded into a precise shape that gives the protein it's function. Enzymes act as biological catalysts. They speed up chemical reactions without being used-up themselves. The names given to enzymes typically end with -ase ==Enzyme Action== [image:http://i.imgur.com/QJiofNY.png?2] Enzymes temporarily combine with the chemicals involved in a reaction. These chemicals are called the ''substrate''. The combination is called the ''enzyme- substrate complex''. When the enzyme and substrate combine, the substrate is changed to a different chemical called the product. The enzyme is not consumed or altered by the reaction. ===Lock & Key Model=== [image:http://i.imgur.com/upWMHow.png?1] The part of the enzyme where the substrate binds is called the ''active site''. Enzymes are highly specific and will only bind one type of substrate. It was originally suggested that this was because an enzyme and substrate both possess specific complementary geometric shapes that fit exactly into one another. This is often referred to as "the lock and key" model. An enzyme only fits one particular kind of substrate in the same way that a lock only fits one particular kind of key. ===Induced Fit Model=== [image:http://i.imgur.com/wwoSvgB.gif] The lock and key model was later revised slightly. Since enzymes are rather flexible structures, the active site is continually reshaped by interactions with the substrate. As a result, the substrate does not simply bind to a rigid active site; the part of the protein which makes up the active site is moulded around the substrate for an even more precise fit. This very slight change in shape (conformation) is what allows the enzyme to carry out its catalytic function.
Credit: Ben Himme