lab 6
TRANSCRIPT
BY: WAN ISKANDAR FIRDAUS B SHAHARIMAN
MUHAMMAD IZWAN BIN NORMAN
ANTHONEO JAY AUGUSTINE
LAB 6: DIGESTION OF STARCH, PROTEIN, AND FATS IN HUMAN
THE HUMAN DIGESTIVE SYSTEM
DIGESTION OF STARCH
WHERE DOES THE DIGESTION OF STARCH
OCCUR?
ORGANS THAT SECRETES ENZYME AMYLASE
Starch Digestion by AmylaseStarch is a polymer composed or repeating units of glucose.
Amylase breaks starch into smaller subunits such as maltose.
Maltose
20cm3 of uncontaminate
d saliva was collected in a
measuring cylinder
Transfer one quarter of the saliva into a test tube and place this test tube in boiling
water for 15 minutes
Transfer a further
quarter of the saliva
into another test tube
Add four drops of
hydrochloric acid, mix well and
leave for at least 15 minutes
Set up six
pairs of test tubes
Leave the test tubes for at least
10 minutes
METHODS
Sugar only Starch onlyStarch
+ untreat
ed saliva
Starch + pre-
heated saliva
Starch + acidified
saliva
Untreated saliva only
TESTS
Iodine test Benedict’s test
Pair
Contents Test with iodine solution
Test with benedict’s reagent
A Sugar only No change Turns brick red color
B Starch only
Turns dark blue No change
C Untreated saliva only
No change No change
D Starch + untreated saliva
No change Turns brick red color
E Starch + pre-heated saliva
Turns dark blue No change
F Starch + acidified saliva
Turns dark blue No change
RESULTS
LAB 6: DIGESTIO
N OF PROTEIN
IN HUMAN
DIGESTION OF PROTEIN
Amino acid
Peptide
Poly peptide
Protein
MATERIALS USED
4 test tubesTest tube rack2 syringes or
pipettes (10 ml)2 syringes or
pipettes (1 ml)Label
pH paperIncubator (37’c)
1% pepsin solution
1% trypsin solution
0.1 M HCL0.2 M sodium
carbonateEgg white
METHOD
The 4 test tubes are labeled; P2, P9, T2, T9Test tubes are set up as follows;
Test tubes are shaken as to mix the content
.
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
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
hoursThe contents are examined and the appearance of the egg white and it’s
surrounding is observed.Results are recorded.
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.
RESULT- FOR PEPSIN VIA BIURET TEST
TEST OBSERVATION INFERENCE
POSITIVE The solution turns from blue to violet( purple)
Presence of peptide bonds in protein
NEGATIVE No change /The solution remains blue
No presence of peptide bonds in protein
RESULT- FOR TRYPSIN VIA MILLION’S TEST
TEST OBSERVATION INFERENCE
POSITIVE The solution turns from blue to pink
Presence of the amino acid tyrosine
NEGATIVE No change /The solution remains blue
No presence of the amino acid tyrosine
IF POSITIVE….
DIGESTION OF FATS
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
preparedTest tube 1:
1% bile (until 6cm mark) + 2/3 drops phenolphthalein + 0.2% NaOH drop by drop until pink
+ 3 drops vegetable oilShake and incubate at 37°C for
1 hour
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
Test tube 3:1% bile (until 6cm mark) + 2/3 drops phenolphthalein
+ 0.2% NaOH drop by drop until pink + 3 drops of oilShake and allow to remain at room temp. for 1 hour
Test tube 1:PinkColourless
Fats are emulsified and digestedTest tube 2:
Pink remainsFats are not emulsified
Test tube 3:Pink remains
Condition not suitableLow temperature
RESULT
» Fats are made of carbon, hydrogen, and oxygen.
FATS
» Fats supply your body with: Energy Form your cells Maintain body temperature Protect your nerves
»Unsaturated Fats have at least one unsaturated bond in a place where hydrogen can be added to the molecule.
UNSATURATED FATS
»Unsaturated fats are usually liquid at room temperature.
»Unsaturated fats are classified as either monounsaturated fats or polyunsaturated fats.
» Fats that have all the hydrogen the carbon atoms can hold are called saturated fats.
SATURATED FATS
» Saturated fats are usually solid at room temperature.
» Too much saturated fat in your diet can lead to heart disease.
» 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.
FAT BREAKDOWN IN THE SMALL INTESTINE
+Water soluble
Emulsifica
tion
Fatty acids
Hydrolys
is
» 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
BILE
• Produced in liver, stored in gallbladder– Except horse
• Alkaline solution composed of:– Bile salts– Cholesterol– Lecithin– Bilirubin
• Responsible for fat emulsification– Detergent action
Fatty acid + glycerol
Lacteal
Lymph