proteins

• • Structural proteins — provide physical support to the cell/organism.
• • Enzymes — biological catalysts which speed up cellular reactions which are vital for life. The enzymes are unchanged in the process.
• • Hormones — act as chemical messengers carrying information from one part of the organism to another.
• • Antibodies — combine with pathogens to destroy them and protect the body from disease.
• • Receptors — are found on the surface of cells and allow signals to be transmitted across the membrane into the cell.
• All enzyme reactions follow the same basic word equation:

  A) substrate

  B) enzyme

  C) product

  
• The substrate is the molecule the enzyme is working on
• The product is the molecule produced at the end of the reaction
• Enzymes act on their substrate by attaching to them. The area on the enzyme where a substrate attaches is called the:

  A) active site

  
• Each enzyme has a different shaped active site and will therefore bind to different substrate(s). As a result enzymes are specific, they will only catalyse one reaction.
• The shape of an enzyme's active site is complementary to the shape of its specific substrate(s). This means they can fit together.
• Degradation reactions involve the breakdown of molecules

  
• Synthesis reactions involve the build-up of molecules 

  
• An enzyme is most active given certain conditions. These conditions are known as the optimum conditions.
• Enzymes and other proteins are affected by temperature and pH.
• The optimum temperature for enzymes within the human body is 37oC.
• In certain conditions an enzyme can become denatured. This is where the shape of the active site changes and will no longer allow the substrate to bind to it. This lowers the rate of reaction.