The document summarizes the human digestive system's breakdown of starch, protein, and fats. It describes how the enzyme amylase breaks down starch into smaller sugars in the mouth and small intestine. For protein digestion, it explains how the enzymes pepsin and trypsin break down protein into peptides and amino acids in the stomach and small intestine. Finally, it outlines how bile emulsifies fats so the enzyme lipase can break fats down into fatty acids and glycerol in the small intestine, allowing for absorption.

1. LAB 6: DIGESTION OF STARCH, PROTEIN, AND FATS IN HUMAN
BY: WAN ISKANDAR FIRDAUS B SHAHARIMAN
MUHAMMAD IZWAN BIN NORMAN
ANTHONEO JAY AUGUSTINE

2. THE HUMAN DIGESTIVE SYSTEM

3. DIGESTION OF STARCH

4. WHERE DOES THE DIGESTION OF
STARCH OCCUR?

5. ORGANS THAT SECRETES
ENZYME AMYLASE

6. Starch Digestion by Amylase
Starch is a polymer
composed or repeating
units of glucose.
Amylase breaks starch
into smaller subunits
such as maltose.
Maltose

7. METHODS
Transfer one
20cm3 of Transfer a further
quarter of the saliva
uncontaminated quarter of the
into a test tube and
saliva was collected
in a measuring
place this test tube saliva into
in boiling water for another test tube
cylinder
15 minutes
Set up
Leave the test
tubes for at
six pairs Add four drops
of hydrochloric
least 10 of test acid, mix well
and leave for at
minutes tubes least 15 minutes

8. Starch +
Starch only
Sugar only untreated
saliva
Starch +
Untreated saliva Starch + pre-heated
only acidified saliva saliva

9. TESTS
Iodine test
Benedict’s test

10. RESULTS
Pair Contents Test with iodine Test with
solution benedict’s reagent
A Sugar only No change Turns brick red color
B Starch only Turns dark blue No change
C Untreated No change No change
saliva only
D Starch + No change Turns brick red color
untreated
saliva
E Starch + pre- Turns dark blue No change
heated saliva
F Starch + Turns dark blue No change
acidified
saliva

11. LAB 6:
DIGESTION
OF PROTEIN
IN HUMAN

12. DIGESTION OF PROTEIN
Protein
Poly peptide
Peptide
Amino acid

13. MATERIALS USED
4 test tubes Incubator (37’c)
Test tube rack 1% pepsin solution
2 syringes or 1% trypsin solution
pipettes (10 ml) 0.1 M HCL
2 syringes or 0.2 M sodium
pipettes (1 ml) carbonate
Label Egg white
pH paper

14. METHOD
The 4 test tubes are labeled; P2, P9, T2, T9
Test tubes are set up as follows;
Test tube Contents
P2(PEPSIN AT pH 2.0) 5cm³ pepsin and 0.5cm³ HCl
P9(PEPSIN AT pH 9.0) 5cm³ pepsin and 0.5cm³
sodium carbonate
T2(TRYPSIN AT pH 2.0) 5cm³ pepsin and 0.5cm³ HCl
T9(TRYPSIN AT pH 9.0) 5cm³ pepsin and 0.5cm³
sodium carbonate
Test tubes are shaken as to mix the content
.

15. A small strip of egg white is added to each of the
test tube
Then, test tubes are placed in an incubator at 37 C
and then leave for 2 hours
The contents are examined and the appearance of
the egg white and it’s surrounding is observed.
Results are recorded.

16. THEORY……
Simply said, pepsin react best at a low pH
value white trypsin react best at high pH
value.
So, protein is best digested via this
respective enzyme at their suitable
pH.

17. RESULT- FOR
PEPSIN VIA
BIURET TEST
TEST OBSERVATION INFERENCE
POSITIVE The solution turns Presence of
from blue to violet( peptide bonds in
purple) protein
NEGATIVE No change /The No presence of
solution remains peptide bonds in
blue protein

19. FOR TRYPSIN
RESULT-
VIA MILLION’S TEST
TEST OBSERVATION INFERENCE
POSITIVE The solution turns from Presence of the amino
blue to pink acid tyrosine
NEGATIVE No change /The solution No presence of the amino
remains blue acid tyrosine

20. IF POSITIVE….

21. DIGESTION OF FATS

22. METHOD
1) The first 3 test tubes are labeled and
marked at 3cm and 6 cm levels. 1% to
2% pancreatic solutions is added to
test tube 1-3 to the 3cm mark. 4 test
tubes are prepared
Test tube 1:
1% bile (until 6cm mark) + 2/3 drops
phenolphthalein + 0.2% NaOH drop by
drop until pink + 3 drops vegetable oil
Shake and incubate at 37 C for 1 hour

23. Test tube 2:
Distilled water (until 6cm mark) +
2/3 drops phenolpthalein + 0.2%
NaOH drop by drop until pink + 3
drops of oil
Shake and incubate at 37 C for 1
hour

24. Test tube 3:
1% bile (until 6cm mark) + 2/3
drops phenolphthalein + 0.2%
NaOH drop by drop until pink + 3
drops of oil
Shake and allow to remain at room
temp. for 1 hour

25. Test tube 1:
PinkColourless
Fats are emulsified and digested
Test tube 2:
Pink remains
Fats are not emulsified
Test tube 3:
Pink remains
Condition not suitable
Low temperature
RESULT

26. FATS
» Fats are made of carbon, hydrogen, and oxygen.
» Fats supply your body with:
 Energy
 Form your cells
 Maintain body temperature
 Protect your nerves

28. UNSATURATED FATS
» Unsaturated Fats have at least one unsaturated
bond in a place where hydrogen can be added to
the molecule.
» Unsaturated fats are usually liquid at room
temperature.
» Unsaturated fats are classified as either
monounsaturated fats or polyunsaturated fats.

29. SATURATED FATS
» Fats that have all the hydrogen the carbon atoms
can hold are called saturated fats.
» Saturated fats are usually solid at room
temperature.
» Too much saturated fat in your diet can lead to
heart disease.

30. FAT BREAKDOWN IN THE
SMALL INTESTINE
» Fats are digested by mixing the fat with the digestive enzyme
lipase (from pancreatic juice), which enters the duodenum
from the pancreas - the main source of enzymes for
digesting fats and proteins.
» Lipase chops up lipid molecules into fatty acid and glycerol.
» Fat does not dissolve in water.
» To overcome this problem the digestive system uses a
substance called bile, produced in the liver but stored in
the gallbladder, which enters the duodenum via the bile duct.
» Bile emulsifies fats - meaning, it disperses them into small
droplets which then become suspended in the watery
contents of the digestive tract.
» Emulsification allows lipase to gain easier access to the fat
molecules and thus accelerates their breakdown and
digestion.

31. +
Water soluble

32. Fatty acids

33. » Absorption of fat into the body occurs in the villi - the millions of
finger-like projections which cover the walls of the small intestine.
» Inside each villus is a series of lymph vessels (lacteals) and blood
vessels (capillaries).
» The lacteals absorb the fatty acids and glycerol into the lymphatic
system which eventually drains into the bloodstream.
» The fatty acids are transported via the bloodstream to the membranes
of adipose cells or muscle cells, where they are stored or oxidized for
energy.
» Fats are only converted to glucose for energy supply during extreme
condition.
» The glycerol part is absorbed by the liver and is either converted into
glucose (gluconeogenesis), and/or used to help breakdown glucose
into energy (glycolysis).
HOW FAT IS ABSORBED INTO
THE BLOODSTREAM

34. BILE
• Produced in liver, stored in gallbladder
– Except horse
• Alkaline solution composed of:
– Bile salts
– Cholesterol
– Lecithin
– Bilirubin
• Responsible for fat emulsification
– Detergent action

36. Fatty acid +
glycerol
Lacteal
Lymph