enzymes & catalysts.

• enzymes are proteins. they are produced in the ribosomes in every cell. their structure is determined by the order of amino acids.
• enzymes can either break down or build up substrates.
• the lock and key theory : each enzyme is specific for one and ONLY one substrate (one lock - one key) The active site is part of the enzyme that fits with the substrate. The active site has a specific fit for this particular substrate and no other.
• Digestive enzymes play a key role in breaking down the food you eat. These proteins speed up chemical reactions that turn nutrients into substances that your digestive tract can absorb.

  Your saliva has digestive enzymes in it. Some of your organs, including your pancreas, gallbladder, and liver, also release them. Cells on the surface of your intestines store them, too.
• Different types of enzymes target different nutrients:

  • Amylase breaks down carbs and starches
  • Protease works on proteins
  • Lipase handles fats
• Enzymes have an active site of a specific shape, like a lock. Substrates also have a specific shape, like a key. The substrate fits into the active site of the enzyme, just like a key fits into a lock. This interaction speeds up the chemical reaction of the substrate(s).
• when particles have an optimum temperature, they collide more often because they move faster. if the catalase and substrate collide more often then the rate of the reaction is faster
• If a protein is heated up too much, then it destroys its 3D structure because bonds are broken. This destroys the shape of the active site of an enzyme. Destroying the shape of the active site means the substrate wont fit so the reaction wont be catalysed.
• Different pHs affect an enzymes shape. If you change the shape of the active site then the enzyme cannot function. Digestive enzymes may have different optimal pHs as they work in different places in the body
• A denatured enzyme refers to an enzyme that has lost its normal three-dimensional, or tertiary, structure. Once an enzyme loses this structure and is denatured, it is no longer able to function.