Enzymes in Digestion (WJEC GCSE Biology)

Revision Note

Emma

Author

Emma

Last updated

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 enzymescarbohydrases, 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 by enzymes into glucose

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

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 lipids to glycerol and fatty acids

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

Examiner Tip

Different enzymes are produced in different regions of the digestive system (including the mouth, stomach and intestines) to break down the large molecules during the digestion process.

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Emma

Author: Emma

Expertise: Biology

Prior to working at SME, Emma was a Biology teacher for 5 years. During those years she taught three different GCSE exam boards and two A-Level exam boards, gaining a wide range of teaching expertise in the subject. Emma particularly enjoys learning about ecology and conservation. Emma is passionate about making her students achieve the highest possible grades in their exams by creating amazing revision resources!