enzyme action

• a protein is formed from a chain of amino acids
• the 3d shape of a protein is caused by folding of the amino acid chain which depends on the sequence of amino acids in the chain.
• the 3d shape of enzymes is important in how they work because within the shape is a small pocket called the active site
• the active site is where the substrate of the enzyme fits at the start of a reaction
• different substrates have different 3d shapes and different enzymes have active sites of different shapes this explains why every enzyme can only work with a specific substrate that fits the active site
• what is the active site of an enzyme?

  The active site of an enzyme is the region where the substrate binds and the chemical reaction takes place.
• why is the active site a different shape in different enzymes?

  The shape of an enzyme's active site is complementary to the shape of its specific substrate
• what is meant by enzyme specifity?

  Enzyme specificity refers to the ability of an enzyme to catalyze a specific reaction with a specific substrate.
• lock and key model

  
• the active site holds the substrate molecules tightly in the right position for bonds to form between them and make a product molecule.
• the product molecule is a slightly different shape to the substrate molecules so it no longer fits tightly in the active site and is released
• when substrate molecules are held in the right position in the active site, the bonds between them are more easily broken and formed
• changes in pH or temperature can affect how the protein folds up, and so can affect the shape of the active site. if the shape of the active site changes too much, the enzyme will no longer work properly. if the active site changes shape too much, the enzyme will no longer catalyse the reaction. - enzyme has been denatured
• explain what denaturing of an enzyme means

  the substrate changes shape and no longer fits in the active site
• systems in humans keep our body temperature constant. using your knowledge of enzymes, explain why this is important


  enzymes in a body's cells must have the correct temperature to be able to catalyse chemical reactions, if the temperature changes, the enzyme will denature