Page 21 - exemple

One hour later, the content of test tube 1 becomes clear whereas test tube 2 remains milky.
Under the effect of pepsin and at 37°C, albumin was hydrolyzed into water soluble substances
called polypeptides.
N.B: The Biuret test doesn’t identify the presence of amino acids.

3 Digestion of lipids

A
Pour in 3 test tubes (A), (B) and (C), water Tube
Oil
and oil. Water + oil

Add bile to tubes (B) and (C) and pancreatic Water
Heavy agitation
juice to tube (C). and let rest
Maintain the 3 tubes at 37°C.
o
T = 37 C
B
Results:
Bile + Droplets
The oil persists and floats on the water surface water + oil of oil
spread
of tube A. in water
Heavy agitation
In tube B, oil is emulsified.
In tube C, oil disappears and is hydrolyzed T = 37 C
o
into fatty acids and glycerol.
C Oil + water
Document 6 shows the variation of the + bile +
Fatty acids
percentage of oil and fatty acids in tube C as a pancreatic and
juice
function of time. glycerol
Heavy agitation
- The bile that is produced at the level of the
liver and is stored in the gallbladder is Doc 5- Digestion of lipids in the presence of
released in the small intestine. It doesn’t the pancreatic juice.
contain any enzyme, its role is to emulsify
lipids and turn the intestinal medium basic. Percentage
100
This facilitates the digestion of lipids.
- The pancreatic juice contains an enzyme, the
lipase, that acts specifically on lipids and 75
transforms them into fatty acids and
glycerol. 50 Fatty acids
- The passage of food in the small intestine
lasts between 3 and 6 hours.
25
- The large intestine contains wastes that
Time
progress slowly (between 1 and 3 days) Oil (hours)
towards the rectum. The wastes are
0 0,5 1 1,5 2 3
eventually eliminated through the anus.
Doc 6- The results of the digestion of lipids by
lipase.

Digestion 25