Question: what is the action of acid and alkali on the enzyme in saliva? Acid: Alkali:   (Procedure and data are already given)

Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
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Question: what is the action of acid and alkali on the enzyme in saliva?

Acid:

Alkali:

 

(Procedure and data are already given)

 

 

Procedure:
1. Label 3 test tubes 1, 2 and 3. Place the substances in each test tube as
indicated below:
Tube
1% starch
0.1M NaCl
Acid/base/water
Saliva
1
10 ml
1 ml
1ml 0.05N HCI
2 ml
1 ml distilled
H2O
2
10 ml
1ml
2 ml
1 ml 0.05N
NaOH
3
10 ml
1 ml
2 ml
2. Mix well by shaking each tube and place in a water bath with
temperature maintained at 40°C for 30 minutes.
3. Remove all tubes from the water bath and stir.
4. Perform iodine test by taking 1 drop from each tube and place in
different holes of a spot plate. Add 1 drop iodine and mix. Note color.
5. Perform benedicts test.
Benedict's – to 1 ml benedict's reagent, add 5 drops of the other half of
each tube and heat in a boiling water bath for 3 minutes. Note color of
precipitate.
6. If the result in iodine test is positive (violet to blue color) and the
benedicts test is negative return the tubes in the water bath and wait
for another 15 minutes.
7. Repeat procedure 4until the blue color of starch with iodine fail to
appear. Note the time of the disappearance of the blue color in iodine
test.
8. Then perform Benedict's test by placing 1 ml of benedicts reagent in a
test tube and add 3 drops of the sample (that is already negative to
iodine). Heat in a boiling water bath for 2 mins. Note color of precipitate
formed.
9. If no brick red precipitate is formed, return the tube in the water bath
(40°C) for 15 minutes.
10. Repeat procedures 8-9 until a brick red precipitate is obtained. Note
time of the appearance of the precipitate.
Transcribed Image Text:Procedure: 1. Label 3 test tubes 1, 2 and 3. Place the substances in each test tube as indicated below: Tube 1% starch 0.1M NaCl Acid/base/water Saliva 1 10 ml 1 ml 1ml 0.05N HCI 2 ml 1 ml distilled H2O 2 10 ml 1ml 2 ml 1 ml 0.05N NaOH 3 10 ml 1 ml 2 ml 2. Mix well by shaking each tube and place in a water bath with temperature maintained at 40°C for 30 minutes. 3. Remove all tubes from the water bath and stir. 4. Perform iodine test by taking 1 drop from each tube and place in different holes of a spot plate. Add 1 drop iodine and mix. Note color. 5. Perform benedicts test. Benedict's – to 1 ml benedict's reagent, add 5 drops of the other half of each tube and heat in a boiling water bath for 3 minutes. Note color of precipitate. 6. If the result in iodine test is positive (violet to blue color) and the benedicts test is negative return the tubes in the water bath and wait for another 15 minutes. 7. Repeat procedure 4until the blue color of starch with iodine fail to appear. Note the time of the disappearance of the blue color in iodine test. 8. Then perform Benedict's test by placing 1 ml of benedicts reagent in a test tube and add 3 drops of the sample (that is already negative to iodine). Heat in a boiling water bath for 2 mins. Note color of precipitate formed. 9. If no brick red precipitate is formed, return the tube in the water bath (40°C) for 15 minutes. 10. Repeat procedures 8-9 until a brick red precipitate is obtained. Note time of the appearance of the precipitate.
EFFECT OF pH ON ENZYME ACTIVITY
Results:
Tube 1
Tube 2
Tube 3
Time in
Minutes
Iodine
Benedict's
Iodine
Benedict's
Iodine
Benedict's
(+)
(orange-red
precipitate)
30
+
+
(+)
15
(orange-red
precipitate)
+
(+)
+
15
(brick-red
precipitate)
(+)
+
15
+
(brick-red
precipitate)
Note: Mark (+) if the blue color appears and (-) if no blue color appears in iodine test.
(+) if precipitate is formed and note the color of the ppt. and (-) if no precipitate is
Transcribed Image Text:EFFECT OF pH ON ENZYME ACTIVITY Results: Tube 1 Tube 2 Tube 3 Time in Minutes Iodine Benedict's Iodine Benedict's Iodine Benedict's (+) (orange-red precipitate) 30 + + (+) 15 (orange-red precipitate) + (+) + 15 (brick-red precipitate) (+) + 15 + (brick-red precipitate) Note: Mark (+) if the blue color appears and (-) if no blue color appears in iodine test. (+) if precipitate is formed and note the color of the ppt. and (-) if no precipitate is
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