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