Enzymes Protein Responsible for most cell functions Functions – to build or break apart – Translate DNA – Breakdown food – Put together macromolecules Very specific – one enzyme for one function – Ends with -ase – Name reflects function lactase breaks apart lactose

Enzyme Action Enzymes have a specific binding site called the active site The molecule or molecules that bind to the active site are called a substrates Some enzymes put two substrates together A + B AB Some enzymes break one substrate apart AB A + B

Active Site Enzyme substrate complex substrate Enzymes do not get used up Reaction stops when there is no more substrate for the enzyme to use

Enzymes are Catalysts Catalyst – a substance that lowers the activation energy of a chemical reaction Reactions involving enzymes will happen with or without the enzyme. Enzymes make the reaction use less energy

Common Enzymes Digestion Muscle contraction Photosynthesis and Respiration Bacterial enzymes Factors that Affect Enzymes Temperature – Too hot – Too cold pH – Acidic conditions