6.8 - Digestive enzymes

Question 1

3 types of proteases:

Answer 1

• Endopeptidases- These hydrolyse internal peptide bonds in the middle of proteins to form shorter polypeptides, increasing the number of ends for other proteases to work on.
• Exopeptidases- These hydrolyse peptide bonds at the ends of polypeptides to remove terminal amino acids or dipeptides.
• Dipeptidases- These break down any remaining dipeptides into amino acids.

Question 2

Role of proteases and what are they produced by?

Answer 2

• proteases/peptidases break down poly/dipeptides or proteinbs into smaller units and eventually into amino acids
• some are produced and act in the stomach but others are produced in the pancreas and act in the small intestine

Question 3

Digestion of lipids

Answer 3

• Bile salts emulsify lipids into tiny droplets called micelles, increasing the surface area of the lipids.
• Pancreatic lipase breaks down micelles into fatty acids and monoglycerides.

Question 4

What do lipases do and what are they produced by?

Answer 4

• break down lipids into fatty acids and monoglycerides
• produced by the pancreas and act in the small intestine

Question 5

membane-bound disaccharidases

Answer 5

bound to epithelial cells that line the ileum

Question 6

examples of disaccharidases:

Answer 6

sucrase
maltase
lactase

Question 7

Example of starch digestion

Answer 7

1. Salivary amylase breaks down starch into the disaccharide maltose in the mouth.
2. Acid in stomach denatures salivary amylase.
3. Pancreatic amylase continues starch digestion in small intestine.
4. The epithelial cells in the ileum lining produce maltase to break down maltose into α-glucose monomers.

Question 8

What do carbohydrases do and where are they produced?

Answer 8

• break down large carbohydrates into smalller poly/di/monosaccharides
• produced by the salivary glands, pancreas and epithelial cells lining the ileum

Question 9

3 type of digestive enzymes

Answer 9

Carbohydrases
Lipases
Proteases

Question 10

What are digestive enzymes?

Answer 10

• involved in chemical digestion
• catalyse hydrolysis reactions - breaks up bonds in large insoluble food molecules to form smaller soluble molecules
• gets absorbed into the bloodstream as a result