Digestion Of Protein And Fat

Question 1

Where are bile salts produced and stored?

Answer 1

Produced in the liver
Stored in the gall bladder

Question 2

What are the functions of bile salts?

Answer 2

• splits lipids into smaller droplets (emulsification)
• lower surface tension of a large fat droplet
• increases the surface area of lipids - speed up lipase action
• neutralises stomach acids

Question 3

Describe the digestion of triglycerides into monoglycerides and fatty acids catalysed by the enzyme lipase

Answer 3

• triglyceride breaks down to form monoglycerides and two fatty acids
• via a hydrolysis reaction
• catalysed by the enzyme lipase (made in the pancreas)
• secreted into the small intestine where they act

Question 4

Describe the digestion of lipids catalysed by both lipase and bile salts

Answer 4

• pancreas releases lipase
• liver releases bile salts
• both lipase and bile salts travel to the small intestine
• bile salts emulsify lipid globules in the small intestine
• makes lipid molecules into smaller droplets
• increases surface area for lipase action
• lipase hydrolyses ester bonds of lipid - forms monoglycerides and fatty acid molecules
• form micelles when associated with bile salts

Question 5

In protein digestion, describe the function of the enzyme endopeptidase and state where it’s released

Answer 5

Hydrolyses peptide bonds between specific amino acids in the middle of polypeptides
Released in the stomach

e.g. pepsin, tripsin

Question 6

In protein digestion, describe the function of the enzyme exopeptidase and state where it’s released

Answer 6

Hydrolyses the peptide bonds at the ends of polypeptides
Released in the small intestine

Question 7

In protein digestion, describe the function of the enzyme dipeptidase and state where it’s released

Answer 7

Hydrolyses peptide bonds in a dipeptide
Released in the small intestine