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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.
*NEXT PAGE* 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.