Edexcel iGCSE Biology-2.29 role of digestive enzymes- Study Notes- New Syllabus
Edexcel iGCSE Biology-2.29 role of digestive enzymes- Study Notes- New syllabus
Edexcel iGCSE Biology-2.29 role of digestive enzymes- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
2.29 understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases
Role of Digestive Enzymes
📝 Introduction
Food molecules are too large to be absorbed directly into the blood.
Enzymes break them down into small, soluble molecules.
These can then pass through the wall of the small intestine into the bloodstream.
🔑 Main Digestive Enzymes
1. Carbohydrases (starch digestion)
- Amylase
- Produced in: salivary glands, pancreas.
- Action: Starch → Maltose (a disaccharide).
- Maltase
- Produced in: small intestine (ileum).
- Action: Maltose → Glucose (monosaccharide).
- Glucose = absorbed into blood, used for respiration.
2. Proteases (protein digestion)
- Pepsin → in stomach, works best in acidic pH.
- Trypsin → from pancreas, works in alkaline conditions in small intestine.
- Action: Proteins → Amino acids.
- Amino acids = used for growth, repair, enzymes, hormones.
3. Lipases (lipid digestion)
- Produced in: pancreas.
- Action: Lipids (fats & oils) → Fatty acids + Glycerol.
- Fatty acids + glycerol = absorbed into lacteals (lymph vessels).
📊 Summary Table
| Enzyme | Where Produced | Substrate | Product | Site of Action |
|---|---|---|---|---|
| Amylase | Salivary glands, pancreas | Starch | Maltose | Mouth, small intestine |
| Maltase | Small intestine (ileum) | Maltose | Glucose | Small intestine |
| Protease (pepsin) | Stomach | Protein | Amino acids | Stomach |
| Protease (trypsin) | Pancreas | Protein | Amino acids | Small intestine |
| Lipase | Pancreas | Lipids (fats & oils) | Fatty acids + Glycerol | Small intestine |
⚡ Quick Recap
Starch → Maltose → Glucose (amylase + maltase).
Proteins → Amino acids (proteases).
Lipids → Fatty acids + Glycerol (lipase).
Small, soluble products = absorbed into blood/lymph.