Enzymes

• Enzymes are made of chains of amino acids.
• A substrate fits on to the active site of of an enzyme and they bind together. The reaction takes place rapidly.
• Enzymes control metabolism.
• Enzymes build large molecules from multiple smaller ones.
• Enzymes break down large molecules into smaller ones.
• Enzymes change one molecule into another.
• Each different type of chemical reaction in the body is controlled by a different type of enzyme.
• Enzymes are biological catalysts. This means that they are substances which speed up chemical reactions without being used up. They are part of the digestive system.
• The Lock and Key Theory is the theory that the substrate must match the active site of the enzyme in order to be broken down into smaller molecules. Enzymes will only catalyse specific reactions.
• Put a drop of iodine in every well of a spotting tile. Set up a Bunsen burner and heat water until it is 35 degrees celsius or use a water bath. Add 1 cm^3 of amylase and 1cm^3 of buffer solution to a boiling tube and heat. After 5 mins, add 5cm^3 of starch solution. Mix the contents and start a timer. Use continuous sampling to record how long it takes for the starch to be broken down. When iodine remains orange, it has all been broken down. Repeat for different pH values.
• Enzymes work best at 37 degrees celsius (body temperature).
• Protease works at pH2. Amylase works at pH7. Protease, amylase and lipase all work at pH 7-8.
• Enzymes catalyse specific reactions in living organisms due to the shape of their active site.
• Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream.
• Carbohydrases break down carbohydrates to simple sugars. Amylase is a carbohydrase which breaks down starch.
• Proteases break down proteins to amino acids.
• Lipases break down lipids (fats) to glycerol and fatty acids.
• The products of digestion are used to build new carbohydrates, lipids and proteins. Some glucose is used in respiration.
• lipids and proteins. Some glucose is used in respiration. Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.