Starch Lab

The purpose of this lab was to test different substances using various procedures to see what biomolecules were present and ultimately find out what restaurant Anna Lyza had eaten at before she died. For the first control test, we used vegetable oil to test for lipids. So, if the solution does not contain lipids, it does not become translucent when placed onto a paper bag square and held up to a light. So, it is a negative result. However, in the presence of lipids, the solution will become translucent when placed onto a paper bag square and held up to a light. Therefore in this case, the result is positive. On the other hand, we used albumin egg to test for proteins in another control test. If the solution does not contain proteins, it will not experience any color change and so it is a negative result. When there are proteins existing in the solution, it will turn bluish/purplish and for this reason it is a positive result. Furthermore in the third control test, we used dextrose to test for simple carbohydrates such as glucose. If the solution does not contain simple carbohydrates, it will not undergo any color change and will remain a blue color. So, it is a negative result in this circumstance. If there are simple carbohydrates present in the solution, the solution will turn reddish and so the result is positive. For the last control test, we used starch solution to test

Did the results support or refute your hypothesis as to which test tube starch contents would convert to sugar first?

-The more dissolved oxygen in the water, the more fish is observed in that area of water.

specific enzyme (Knowles, 1991). One part of the enzyme, salivary amylase, is that alpha amylase is in the saliva of most animals because this enzyme breaks down starch (Jacobsen, Melvaer, Hensten- Pettersen, 1972). In the presence of starch, this enzyme is present in saliva, but is not present when there is no starch present (Jacobsen, Melvaer, Hensten- Pettersen, 1972). The conditions for salivary amylase to have a reaction with starch would change in temperature and enzyme concentration, as well as, monitoring the pH levels (Jacobsen, Melvaer, Hensten- Pettersen, 1972). Salivary amylase is an enzyme is human saliva that helps in digestion of specific substrates, such as starch (Hudman, Friend, Hartman, Ashton, Catron, 1957). It breaks down starch molecules by splitting maltose from the non-reducing end of a gluten molecule (Jacobsen, Melvaer, Hensten-Pettersen, 1972).

Macromolecules are present in each of the five foods being tested which are pretzels, green peas, apple juice, biscuit mix and bacon bits. To determine this, reagents for the four macromolecules are being used which are Benedict’s, Iodine, Sudan IV and Biuret Solution. The independent variable in this experiment are the different foods being tested. The dependent variable in this experiment is the presence of the macromolecules.

When glucose comes in contact with Benedict's solution and is heated, the color of the solution turns into a mango-orange, which did occur with the solution in the beaker, indicating the presence of glucose. Meanwhile, when starch interacts with iodine (Lugol’s solution), a green hue is apparent; however, it quickly transforms into an opaque black. Because glucose was smaller in size, as it is formed with only one saccharide, it was capable of moving through the dialysis tube into the beaker. This was assumed as the mass of the dialysis tube decreased from 60.06 grams to 59.92 grams, and since the solution in the beaker did not turn in blackish, which indicated direct contact between iodine and starch, a bit of glucose travelled out. In addition, according to the results, starch was unable to because its molecules were too large to travel through the pores of this semi-permeable membrane, as it is formed with more than two simple

In this lab experiment the action of the enzyme Amylase was observed on starch (the substrate). Amylase changed the starch into a simpler form, the sugar maltose, which is soluble in water. Maltose then breaks down the glucose chains of starch in the pancreas and intestines. Amylase is present in human saliva, and begins to act on the starch in the food while still in the mouth. Exposure to heat or extreme PH (acid or base) will denature proteins. Enzymes, including amylase, are proteins; if denatured enzymes can no longer act as a catalyst for the reaction. In the presence of potassium iodide, starch turns a dark purple color; however maltose does not react with I2KI. The rate of fading of starch allows a quantitative measurement of reaction rate.

Record observations: what color did the solution turn? Orange or blue/ black? This will tell whether the amylase is able to denature the starch solution Orange=Negative Blue/black= Positive

Sample of 3 foods selected for the experiment are Brown Rice, Green spiral pasta and Sweet potato, Brown rice was chosen and predicted to show slow release of enzyme having a lighter colour. Of which these three food contain starch at the very start of the experiment.

In this lab our group observed the role of pancreatic amylase in the digestion of starch and the optimum temperature and pH that affects this enzyme. Enzymes are located inside of cells that increase the rate of a chemical reaction (Cooper, 2000). Most enzymes function in a narrow range of pH between 5 through 9 (Won-Park, Zipp, 2000). The temperature for which enzymes can function is limited as well ranging from 0 degrees Celsius (melting point) to 100 degrees Celsius (boiling point)(Won-Park, Zipp, 2000). When the temperature varies in range it can affect the enzyme either by affecting the constant of the reaction rate or by thermal denturization of the particular enzyme (Won-Park, Zipp, 2000). In this lab in particular the enzyme, which was of concern, was pancreatic amylase. This type of amylase comes from and is secreted from the pancreas to digest starch to break it down into a more simple form called maltose. Maltose is a disaccharide composed of two monosaccharides of glucose. The presence of glucose in our experiment can be identified by Benedicts solution, which shows that the reducing of sugars has taken place. If positive the solution will turn into a murky reddish color, where if it is negative it will stay clear in our reaction. We can also test if no reduction of sugars takes place by an iodine test. If starch is present the test will show a dark black color (Ophardt, 2003).

Solutions and color reaction for Benedict’s test for reducing sugars and 2 iodine test for starch

Which of the foods that you tested contained amylase? Which did not? What experimental evidence supports your claim?

During the Benedict's test, the contents of tube B did not change, indicating the absence of sugar in that particular substance. However, the contents of tube A did change orange indicating the presence of sugar in that substance. During the Lugol's test, the content of tube A did not change dark purple indicating the absence of starch in that substance However, the content of tube B changed to dark purple

In order to identify what food, and ultimately from which restaurant Parry ate the day of his poisoning, four experiments were carried out. Each experiment tested for the presence of the following four macromolecules in Parry’s vomit:

Science Lab Essay Light is everywhere. Surviving without light now days would be difficult. If we shine light at various transparent objects of varying density, the light will bend more when it moves through an object of greater density. I need to know how light behaves as it passes through objects of varying densities because I am stealing the painting of Mona Lisa. I will need to know how to deactivate the lights around the painting.