Digestion Lab Discussion

The basic idea of the lab is to conduct an experiment observing gastric digestion, intestinal digestion of starch, intestinal digestion of proteins and lipids, and absorption in the small intestine in order to understand the process of digestion. The conditions of the gastric digestion test included being placed in an incubator at 37-40C for 45 minutes. 5 ml of pepsin solution, hydrochloric acid, and artificial gastric juice each were added separately to each test tube. After it was removed from the incubator, six drops of Biuret reagent was added to each test tube. For the intestinal A digestion of starch test, conditions included adding 5 ml of starch solution to each test tube. Each tube was filled with starch solution, but the conditions in which they remained differed; test tube 1 was left in room temperature, test tube 2 was placed in a 40C incubator, and test tube 3 was placed in a 75C water bath.

After, three drops of iodine-potassium iodine solution were added to all three containers. The conditions for the intestinal digestion of proteins and lipids included adding 10 ml of litmus milk solution was added to each test tube. For test tube 1, one scoop of pancreatin powder was added, a few drops of distilled water was added to test tube 2 and both were placed in a 37-40C incubator for 45 minutes. The conditions for the absorption in the small intestine included the equal addition of starch solution and glucose solution to the dialysis tubing in which it was submerged in distilled water. Then 20 drops of Benedict’s solution was added to the vial in which it was then placed in boiling water.

It is hypothesized that protein digestion will occur in the presence of gastric juice but not in the presence of pepsin juice or hydrochloric acid. The predicted color reactions included that the Biuret reagent reacts with the products of gastric protein digestion (amino acids) to give a pink to violet color (Carolina Biological, 2005). When tested, individual observations included that the substance was clear colored in test tube 1, the pepsin solution, therefore no digestion occurred. For test tube 2, the hydrochloric acid, a clear color was present therefore no digestion occurred. For test tube 3, the gastric juice, a white color was observed showing positive results for the occurrence of digestion. Group results resulted in for test tube 1, 4/4, or 100% of the groups had negative results for digestion which was expected. For test tube 2, 4/4, or 100% of the groups tested negative for digestion which was predicted and for test tube 3, 4/4, or 100% of the groups tested positive for gastric digestion which was expected.

The hypothesis states for intestinal A pancreatic juice will digest starch, at 22C room temperature and 40C body temperature but will not digest at a temperature greater than or equal to 75C. In the presence of starches, iodine-potassium iodine changes from bright yellow to blue-black. In the test tubes, the presence of starch is indicated by a purple-black color. The absence of starch is indicated by a light brown color (Carolina Biological, 2005). Individual results included that for test tube 1 which was placed in room temperature, a blue or blackish color occurred indicating the negative presence of digestion. In test tube 2 which was placed in an incubator was observed to be blue and blackish also, which tested negative for digestion. Test tube 3 which was placed in the water bath resulted in a blue and blackish color also. For group results, 4/4, or 100% of the groups tested negative for digestion in test tube 1 which was not predicted, 4/4, or 100% of the groups tested negative in test tube 2 which was not expected, and 4/4, or 100% of the groups tested negative for digestion in vial 3 which was predicted.

For intestinal digestion B, it is hypothesized that litmus milk will change color in the presence of pancreatin indicating digestion, but not in the presence of distilled water. The milk will turn blue when basic, and red when acidic. The litmus in the milk indicates the presence of acid by a color change from light gray to dark pink-purple (Carolina Biological, 2005). Individual results included that in test tube 1, the color turned a light purple indicating the positive presence of digestion for pancreatin powder. For test tube 2, the color turned a purplish black which indicated a negative result for the presence of digestion with the addition of distilled water. Group results concluded that 4/4, or 100% of the groups tested positive for digestion in test tube 1 which was expected, and 4/4, or 100% of the groups received negative results for digestion in test tube 2 which was predicted.

It is hypothesized that for the absorption in the small intestine test, sugar will pass through dialysis tubing but starch will not. When heated, Benedict’s solution reacts with glucose to produce a red-orange precipitate (Carolina Biological, 2005). Individual observations include that the absorption in vial 2 turned orange, indicating a positive presence of digestion, and for test tube 1, it was observed to turn orange in which it turned out to be negative for the presence of digestion. The group results for the absorption of the small intestine included that 4/4, or 100% of the groups received positive results for the presence of digestion in vial 2 which was as predicted and 3/4, or 75.0% of the groups tested negative for the presence of digestion in test tube 1 which was expected.

An improvement that could be made to make this lab more efficient and precise would be to make the addition of an equal amount of starch and glucose solution more precise to get more accurate results. Another improvement would be for the gastric digestion test, to have a thinner stirrer to mix the powdered albumin better with each solution because it was difficult to get the contents in the tube to mix together when it was sticking all to the thick stirrer. Another improvement that could be made would be to control the room temperature to an exact degree in order to record and control precise results when dependent on room temperature for a condition in a test. A new idea that could be made to this lab would be to test each of the different tests in cold temperatures or conditions to see if that has any affect on the digestion.

Conclusion:

It is hypothesized that protein digestion will occur in the presence of gastric juice but not in pepsin or hydrochloric acid; pancreatic juice will digest starch at 22C room temperature and 40C body temperature but not at temperatures greater than or equal to 75C; litmus milk will change color in the presence of pancreatin indicating digestion. Furthermore, it is hypothesized that sugar will pass through dialysis tubing but starch will not (Taylor, 2009). Overall, the data supports the hypothesis as it was shown to support 77.50% of the hypothesis statement. I enjoyed this lab because I thought it was interesting to see the entire color changes indicative to the many conditions and factors that went into each test.