Identifying macromolecules Essay Example

to a dark blue-black color change ("Starch-iodine test," 2008). Therefore, since both solution 8 and the starch solutions undergo this reaction, we can expect that solution 8 will also turn blue-black when treated with iodine solution.

Adding Iodine solution to glycogen solutions results in a red-brown color due to their similar chemical structure. This is because both glycogen and amylopectin have acetal linkages, causing the highly branched structure of glycogen. As a result, when combined with Iodine solutions, glycogen exhibits a red-brown color (Ophardt, 2003). Therefore, solution 7, which is a glycogen solution, should also show this red-brown color upon addition of Iodine solution. However, the composition of solution 12 or unknown 318 remains uncertain. To determine the presence of reducing sugars in these solutions, the Benedict's Test can be used.

Reducing sugars contain aldehyde or ketone groups that undergo oxidation and conversion into carboxylic acids. The Benedict's solution contains blue Cu+2 ions, which react with these groups, leading to the reduction of Cu+2 ions to Cu+ ions. As a result, a red-brown precipitate called Copper (I) Oxide is formed (Hunt, n.d.). The color change to red-brown indicates the presence of sugars. Honey, being solution 4 among the 12 solutions, is expected to produce a red-brown color due to its sugar content.

All solutions, including glucose (solution 1), maltose (solution 3), sucrose (solution 5), and lactose (solution 6), will result in a red-brown coloration due to their sugar content. The color of solution 12 after the test is uncertain. To identify proteins in a solution, the Biuret Test involves adding 2 mL of a 10% NaOH solution and 5 drops of a

1% CuSO4 solution to each test tube. Proteins are formed by amino acids linked together with peptide bonds.

The polypeptide backbone consists of Nitrogen from the amino group of the amino acid, the ? -carbon, and the carbonyl carbon from the carboxyl group (Pollard ; Earnshaw, 2004). When Cu+2 ions from the CuSO4 solution bind to the Nitrogen atoms of the amino group, protein solutions turn violet (McRae, n. d.). Out of the 12 solutions, only solution 9 should turn violet as it contains a protein solution. The other solutions are not expected to change color, and it is currently unknown whether the unknown 318 solution will change color.