4. Proteins

• Proteins are made of amino acids joined together.
• The variety of protein shapes and functions depends on the sequence of amino acids.
• Proteins are found in 5 Main Groups

  1. S - Structural
  2. H - Hormones
  3. A - Antibodies
  4. R - Receptors
  5. E - Enzymes
• Structural proteins are used to give support to cellular structures. An example of this would be the proteins found in the cell membrane.
• Hormones are chemical messengers that carry specific messages through the bloodstream. An example of this would be insulin signalling to the liver to store excess glucose in the form of glycogen.
• Antibodies defend against pathogens such as bacteria and viruses. An example of this would be antibodies that provide a specific defence against viruses.
• Receptor proteins allow cells to recognise specific substances. For example, liver cells have receptors for signals sent by insulin.
• Enzymes speed up chemical reactions in the cell. For example, starch is broken down into maltose using amylase in the digestive system.
• Enzymes are made up of proteins, they speed up chemical reactions.
• Enzymes are produced by living cells and are unchanged during a chemical reaction.
• In order to work, enzymes must bind to a molecule called its substrate. An enzyme only has one specific substrate, no other ones fit.
• The specific substrate binds to the enzyme at its active site and a product is produced by the reaction.
• Using a enzyme to break down a large molecule to a small molecule is called a degradation reaction.

  
• Using a enzyme to build smaller molecules into a larger molecule is called a Synthesis reaction.

  
• The conditions where the enzyme works best at is its optimum condition.
• If the enzymes condition goes beyond the enzymes optimum, the enzyme will then denature and stop working.