Q. 195.0( 2 Votes )
(a) Name the bran
Starch is the main storage polysaccharide of plants. Polysaccharides are carbohydrates made up of more than three sugar units. It is a polymer of - glucose and consists of two components— amylose and amylopectin. Amylopectin is the major brached chain polymer which consists of - D - glucose units.
Structure of amylopectin
(b) It differs around the second carbon atom wherein β-D-ribose presence of Hydrogen and OH group on 2nd carbon atom whereas in β-D-2-deoxyribose, on the 2nd carbon atom 2 hydrogen atoms are present.
(c) Two peptide linkages are present in a tripeptide.
Three peptide molecules are held by two peptide bonds in between first and second and second and the third molecule.
Some reactions of glucose cannot be explained by its chain structure like -
•Glucose does not answer 2,4 - DNP test.
•It also doesn’t answer Schiff's reagent test.
•The pentaacetate group in glucose does not react with the hydroxylamine.
•Glucose also doesn’t form the hydrogen sulfite addition product with NaHSO3.
REASON: The first three reactions occur in spite of it having an aldehyde group. This happens because the aldehyde group in it is not a free group and is therefore proving that it is in a cyclic structure.
The last test indicates the absence of free - CHO group.
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