Give the plausible explanation for the following: (a) Glucose doesn.t give 2, 4-DNP test. (b) The two strands in DNA are not identical but are complementary. (c ) Starch and cellulose both contain glucose unit as monomer, yet they are structurally different.

Give the plausible explanation for the following: (a) Glucose doesn.t

1.	Give the plausible explanation for the following: (a) Glucose doesn.t give 2, 4-DNP test. (b) The two strands in DNA are not identical but are complementary. (c ) Starch and cellulose both contain glucose unit as monomer, yet they are structurally different.
Answer» Solution :(a) Glucose doesn.t give 2, 4-DNP test The aldehydic group in glucose is not FREE as per the cyclic structure of glucose. Therefore, it does not give 2, 4-DNP test. (b) The two stands are complementary to each other because the hydrogen BONDS are formed between specific pairs of bases. Adenine forms hydrogen bond with thymine whereas cytosine forms hydrogens bonds with guanine. (c ) Starch CONSISTS of amylose and amylopectin. Amylose is a long UNBRANCHED CHAIN of `alpha-D-(+)-`glucose units held together by 1, 4-glycosidic linkage. Amylopectin is a branched chain polymer of `alpha-D-`glucose units in which the chain is formed by `C1-C4` glycosidic linkage. Cellulose is a straight chain polysaccharide composed of `beta-D-`glucose units which are joined by glycosidic linkage between C1 of one glucose unit and C4 of the next glucose unit.