Macromolecules prelab questions (prelab continues onto next page!!!) In this wee

Question

Macromolecules prelab questions (prelab continues onto next page!!!) In this weeks' lab you are asked to work with a number of reagents. For each of the indicated reagents below, determine what it is. Gelatin, for example, is collagen; peptides and protein. Knowing this will help you decipher if the test results you get in lab, are appropriate, or if you have false positive/negative result. A Fructose is a , and as such should yield a positive result for the , and as such should yield a positive result from the , and as such should yield a positive result from the test, which turns in color. B-Glycine is a test, which turns in color. C - Peptone is a test, which turns in color. Which test is specifically for looking for the presence of starch? is a positive result in color. The only macromolecule group test results which can go down the sink this week are for the tests. 47 I P a g e

Explanation / Answer

A The , Fructose is a reducing monosaccharide, and as such should yielda positive result for the Benedict's test, which turns purple in colour. [All monosaccharides are reducing in nature and gives positive result in Benedicts test by reducing the cupric ion to cuprous ion].

B. Glycine is an amino acid, and such should yield a positive result from Ninhydrin test, which turns blue in color.

C. Peptone is a hydrolysed protein, and such should yield positive result from Biuret test, which turns violet in color.

D. Specific test for identification of starch is Iodine test. The iodine reacts with starch due to the formation of an intermolecular charge-transfer complex. It turns "blue-black" in color.

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