AQA GCSE Role of Enzymes in Digestion(Biology)
Role of Enzymes in Digestion
Digestion is the process of breaking down large insoluble molecules into smaller soluble ones which can be absorbed into the bloodstream.
Chemical digestion uses enzymes to speed up the chemical reactions to break down large molecules into smaller ones which can be absorbed into the bloodstream.
After absorption the products of digestion are used to build new carbohydrates, lipids and proteins. Some of the glucose is used in respiration to release energy.
Types of digestive enzymes
There are three main types of digestive enzymes
1.Carbohydrases
2. Lipases
3. Protease
Carbohydrases
Carbohydrases are a type of enzyme that breaks down carbohydrates into sugars.
Amylase is a specific example of a carbohydrase, which breaks down starch into sugars.
Amylase is produced by the salivary glands and is used in the mouth. It is also produced by the pancreas and is used in the small intestine, specifically the duodenum.
Lipases
A lipid (fat) is made up of a glycerol unit bonded to 3 fatty acids.
Lipases are a type of enzyme which breaks down lipids (fats) into glycerol and fatty acids.
Lipase is produced in the pancreas, the lipase then flows via the pancreatic duct into the small intestine where it is used.
Lipase is also made in the small intestine and used in the small intestine.
In the diagram below, a lipid is broken down to glycerol and 3 fatty acids by the enzyme lipase.
Proteases
Proteases are a type of enzyme that breaks down protein into amino acids.
Protease is produced and used in both the stomach and small intestine.
Protease is also produced in the pancreas. Any protease that is made in the pancreas, flows via the pancreatic duct into the small intestine where it is used.
| Name of enzyme | Substrate | Product | Enzyme is produced | Enzyme is used |
|---|---|---|---|---|
| Carbohydrase (Amylase) | Starch | Sugars | Saliva | Mouth |
| Pancreas | Small intestine | |||
| Protease | Protein | Amino acids | Stomach | Stomach |
| Pancreas | Small intestine | |||
| Small intestine | Small intestine | |||
| Lipase | Lipids (fats) | Glycerol + Fatty acids | Pancreas | Small intestine |
| Small intestine | Small intestine |
Practice Questions
1.Explain why enzymes are essential for digestion
2. State the role of carbohydrase enzymes within digestion
3. Which enzyme(s) would be used to break down sunflower oil?
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