Enzymes and digestion

• The pancreas secretes enzymes into the small intestine to break down carbohydrates, proteins, and fats.
• Carbohydrases are produced by the salivary glands and pancreas to hydrolyze starch into maltose, sucrose, and lactose.
• Proteinases (pepsin) from the stomach and trypsin from the pancreas hydrolyze proteins into amino acids.
• Lipase is secreted by the pancreas to hydrolyze lipids into fatty acids and monoglycerides.
• Bile salts emulsify large globules of fat into smaller droplets, increasing surface area for lipase action.
• Bile is released by the liver and stored in the gallbladder, where it emulsifies large globules of oil into smaller droplets that can be acted upon by lipase.
• Enzyme activity can be affected by pH levels temperature and concentration of substrate
• The liver releases a chemical called bile into the intestines , it breaks down lipids in the food.
• The small intestine has villi which increase its surface area so more nutrients are absorbed.
• Villi have microvilli on their surfaces which further increases the surface area available for absorption.
• The lining of the small intestine contains enzymes such as lactase, maltase and sucrase which break down carbohydrates into simple sugars.
• Microvilli contain enzymes such as amylases which break down carbohydrates into simple sugars.
• The substrate for carbohydrates is glucose
• The substrate for protein is amino acids
• The substrate for lipids is 3 fatty acids and glycerol
• To test for sugars Benedict solution is used and turns a red colour if present
• If there are no reducing sugars it will turn blue/green
• To test for starch, add iodine solution to the sample and heat. If starch is present, the solution will turn blue-black
• To test for proteins add biuret solution and if present it will turn from blue to purple
• To test for fats add a few drops of Sudan III to the sample and a red layer will show if present
• To test for lipids add ethanol and shake. If lipids are present, the solution will turn cloudy
• The mouth brings the digestion of carbohydrates , the stomach begins the digestion of proteins
• The large intestine is the last part of the digestive system. It absorbs water from undigested food and forms faeces.
• Enzyme reactions work best at normal temperature