1. Lesson #11: Enzymes in digestion
Objective:
- Identify the main enzymes in digestion and their functions

2. Practical Label the boiling tubes A & B
Fill each tubing with 8ml of starch.
Wash one of the tubes very well and place it in boiling tube A.
Add 3ml of amylase solution in the other tube. Shake. Wash very well and place in boiling tube B.
Place both boiling tubes in the water bath for 30 minutes.
Test the water in the boiling tube for starch and glucose using iodine and benedict’s solution
Record your results.

3. Digestive Enzymes There are 3 main types of digestive enzymes: Enzyme
Reaction catalysed
Where produced
Amylase
Starch → sugars
Salivary glands, pancreas, small intestine
Protease
Proteins → amino acids
Stomach, pancreas, small intestine
Lipase
Lipids → fatty acids + glycerol
Pancreas, small intestine

5. Digestive Enzymes
Amylase
Glucose
Starch
Protease
Amino Acids
Protein

6. Digestive Enzymes Fatty Acids Fat and Glycerol Lipase Fatty Acid

7. The enzyme fits over the substrate perfectly – like a key fits a lock.
Amylase enzyme
Starch molecule
It holds the starch molecule in place as a water molecule breaks the bond between two glucose particles

8. This continues until the molecule has been broken down completely

9. Digestion Summary Chemical digestion:
Salivary amylase: starch  maltose
Pepsin in stomach: protein  peptides
Pancreatic amylase: starch  maltose
Trypsin from the pancreas: protein  peptides
Lipase from the pancreas: fats  glycerol + fatty acids

10. What factors affect the rate of reaction of enzymes
How do you think you can speed up the rate of an enzymic reaction? (Hint: It’s the same as any other reaction!)