Enzymes in Digestion (WJEC GCSE Biology)

Carbohydrase, Protease & Lipase

• The purpose of digestion is to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream

• Large insoluble molecules, such as starch and proteins, are made from chains of smaller molecules which are held together by chemical bonds. These bonds need to be broken

• Enzymes are biological catalysts – they speed up chemical reactions without themselves being used up or changed in the reaction

• There are three main types of digestive enzymes – carbohydrases, proteases and lipases

Carbohydrases

• Carbohydrases break down carbohydrates, like starch, to simple sugars, such as glucose

• There are several different types of carbohydrase enzymes

  • Amylase is one example

• Amylase is made in the salivary glands, the pancreas and the small intestine

The action of carbohydrase enzymes diagram

The digestion of starch to glucose by carbohydrase enzymes

Proteases

• Proteases are a group of enzymes that break down proteins into amino acids

• Protein digestion takes place in the stomach and small intestine, with proteases made in the stomach (pepsin), pancreas and small intestine

The action of protease enzymes diagram

The digestion of proteins to amino acids by protease enzymes

Lipases

• Lipases break down fats and oils (lipids) to glycerol and fatty acids

• Lipase enzymes are produced in the pancreas and secreted into the small intestine

The action of lipase enzymes diagram

The digestion of fats and oils to fatty acids and glycerol by lipase enzymes