enzymes. ( key concept. )

• catalyst.


  a substance that changes the rate of a chemical reaction without being changed by the reaction itself.
• enzyme.


  proteins that function as biological catalysts, meaning they speed up reactions without being used up.
• substrate.


  a molecule that an enzyme reacts with.
• active site.


  the part of the enzyme to which a specific substrate can attach or fit on to.
• lock + key model.


  the enzyme's active site and the shape of the substrate molecule are complementary to one another.
• diagram of the lock and key theory:

  the substrate fits exactly into the active site, creating an enzyme-substrate complex. then, the reaction takes place and an enzyme-product complex is formed. finally, the products are then released.

  
• denaturing enzymes.


  if enzymes are exposed to extremes of pH or high temperatures, the shape of their active site may change. if this happens, the substrate will no longer fit into the enzymes. we say that the enzyme has been denatured.
• temperature in enzymes.

  as the temperature increases, so does the rate of enzyme activity. an optimum activity is reached at the enzyme's optimum temperature. a continued increase of the temperature during enzyme activity results in the enzyme's active site changing shape. it is now denatured.
• carbohydrates.

  • include starch and glucose
  • produced in the mouth ( saliva ), pancreas and small intestine.
• proteins.

  • large molecules made from amino acids.
  • protease are responsible for breaking down our food into amino acids.
  • produced in your stomach, pancreas and small intestine.
• lipids.

  • fats and oils.
  • lipase break down lipids into fatty acids and glycerol.
  • produced in your pancreas and small intestine.