Salivary Amylase Lab
In this laboratory, I observed the process
by which salivary amylase, an enzyme
secreted by the salivary glands in the
mouth, breaks starch down into maltose.
This requires a relatively
straightforward experiment with only a couple of
indicators, some test tubes,
and a starch source. To understand the process, one
has to understand
chemical reactions with enzymes and the its major role in the
digestive
system of the human (Chapter 37). Just to refresh the reader, I will
define a
few words that will appear later on in the lab. Starch is complex
compilation
of simple sugars (or a polysaccharide) that when broken down into
simpler
substance, forms two-sugar maltose (a disaccharide). The enzyme required
to
break down starch, only by simple mixing, is salivary amylase, as
described
above. The two indicators used in this experiment are chemicals
that indicate
the presence of the corresponding substances, starch and
maltose. Iodine
indicates starch with a color change from reddish-brown to
black. Benedict’s
indicates maltose with a color change from translucent blue
to orange-yellow
(with the aid of heat). I will give my hypotheses and the
predictions for the
results of the experiments. The first experiment called
for the mixture of
saliva and oatmeal in two test tubes, one for testing
starch and one for testing
sugar. I hypothesize that the iodine will indicate
positive for starch and the
Benedicts will indicate positive for maltose.
The second experiment called for
the testing of saliva for starch and sugar,
in separate test tubes. I think the
test of iodine and Benedict’s will both
be negative. The third and final
experiment is a mixture of oatmeal and H20
(water); I predict the Method In this
lab, the following materials were used
to understand better enzymatic/digestive
activity with saliva: -Pinch of
Oatmeal -Mortar and pestle -A volunteer to
supply the needed saliva -Saliva (
mL) -Six test tubes -Preferably Distilled
Water ( mL) -Five drops in each
test tube of Benedict’s Solution -Five drops
in each test tube of Iodine
-Tube rack -Hot plate -Beaker with boiling water put
on hot plate Procedure
& Results This section gives a systematic, detailed
explanation on how
the experiment was carried out and what happened afterwards.
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NOTE: I will sometimes refer to maltose as sugar (and visa versa)
as
according to the experiment. Procedure SET UP TEST TUBES LIKE SO: 1) Make
sure
the proper materials listed above are prepared (put tubes in tube rack
and start
setting up the boiling water beaker) 2) Place the required amount
of oatmeal in
the mortar and pestle and start grinding the oatmeal into a
powder. 3) At the
same time let the volunteer(s) rinse their mouth with water
from the water
fountain and then begin to drain saliva into the designated
beaker. 4) When
finished with the drainage, put the correct amount of saliva
into the
corresponding test tubes. 5) Take the powdered oatmeal and place it
in the
designated test tubes. 6) Take the predetermined amount of water and
put it in
the designated test tubes. 7) Place five drops of Benedicts in each
of the
designated containers and place the tubes in the heated beaker for a
few minutes
or until results. 8) Record results. 9) The next step is to place
five drops of
iodine in the designated test tubes and wait for results. 10)
Record results.
11) Experiment procedures are complete. Results &
Discussion By comparing
all of the results, one can tell that most of my
hypotheses were correct. I will
start by listing the results explaining how I
came across these amended
hypotheses. (+) and (-) stand for positive and
negative test results Iodine=test
for starch, Benedicts=test for sugar Saliva
& Oatmeal TT1: Iodine (+) /
Color - blue/black TT2: Benedicts (+) /
Color – green/orange Saliva TT3:
Iodine (-) / Color – Yellow TT4:
Benedicts (-) / Color – Blue Oatmeal &
H20 TT5: Iodine (+) / Color –
blue/black TT6: Benedicts (-) / Color – blue I
predicted that the mixture of
saliva and oatmeal would yield positive results
for both the iodine and the
Benedicts test. My hypothesis was correct. My next
prediction was that the
iodine and Benedicts tests for saliva would both turn
out negative; I
postulated correctly again. The last pair of tubes containing a
mixture of
oatmeal and H20 were also tested with iodine and Benedicts; I
predicted that
the iodine would be positive but the Benedicts would result
negative; I was
correct once again in my hypotheses. I will now discuss how I
came to these
predictions. The first test was with a mixture of saliva and
oatmeal. I
realized almost immediately that sugar, and also starch, would be
present. I
learned from Chapter 37 in the textbook the enzyme salivary amylase
in saliva
would react and break down most of the starch in the oatmeal into
maltose.
The reason not all of the starch was broken down was because I also
learned
previously that an enzyme (salivary amylase) can only handle so much of
the
given substrate (oatmeal starch) before it is exhausted. So, I was right
in
thinking that there would be an indication of both maltose and starch. In
the
second test, I knew right away that there wasn’t going to be any starch
or
sugar in the saliva because: 1) The volunteers rinsed their mouth out
before the
experiment. 2) The saliva contains only the enzyme and not the
substrate or
product. So, the saliva definitely did not have starch or sugar.
And finally
there was the test with the oatmeal and water. I know that the
oatmeal contains
starch and not maltose and the water does not have any of
these substances. This
test was merely to show that oatmeal had starch, which
the positive iodine test
proves clearly. To conclude, I would like to say
that I feel this was the most
lucid and clear laboratory that we have done up
to this point and there really
shouldn’t be any changes to it.