Biological Molecules Lab Report Example | Topics and Well Written Essays - 500 words

Biological Molecules - Lab Report Example Because the functional groups exhibit characteristic chemical reactions that involve color changes, they can be used as the basis of both qualitative and quantitative assessments. Mash a sample of the imitation crab meat in some water with the homogenizer. Remove some of the liquid and place it in a clean test tube or other suitable glass container. To another such container add the equal amount of plain water. Test both solutions with diabetic glucose tests strips. Add Benedicts solution to both containers and heat using water bath. Observe color change identifying presence (or absence) of glucose in solution. A positive result with the water extract indicates that the imitation crab meat contains additional glucose and should be avoided by Granny. 1. Samples should be heated in Benedicts test to increase the rate of the reaction between the sugar and Benedicts reagent. Without heating the reaction may proceed only very slowly, which may lead to a false result. 2. The copper ions in the copper sulfate of Benedicts reagent bond non-covalently or coordinate to the aldehyde functional group of glucose and similar sugars. This facilitates an oxidation of the organic molecule to the carboxylic acid, and is accompanied by the formation of atomic copper by reduction of the copper ions. The presence of copper atoms in the solution is responsible for the observed color changes. Similarly, the copper ions in Biurets solution coordinate to an amide linkage of protein to form a large complex ion that is highly colored. The IKI reagent in the starch test can be thought of as a complex of potassium ions and iodide ions that have captured molecules of iodine (I2). The multiple -OH groups presence on the starch molecules bond non-covalently to the iodine molecules to form a very dark colored complex. 3. If KOH or NaOH were omitted from the Benedicts test, no result could be expected. The hydroxide ion must be present