Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
The amount of branching (number of (α1→6) glycosidic bonds) in amylopectin can be determined by the following procedure. A sample of amylopectin is exhaustively methylated—treated with a methylating agent (methyl iodide) that replaces the hydrogen of every sugar hydroxyl with
a methyl group, converting —OH to —OCH3 . All the glycosidic bonds in the treated sample are then hydrolyzed in aqueous acid, and the amount of 2,3-di-O-methylglucose so formed is determined.
(a) Explain the basis of this procedure for determining the number of (α1→6) branch points in amylopectin. What happens to the unbranched glucose residues in amylopectin during the methylation and hydrolysis procedure?
(b) A 258 mg sample of amylopectin treated as described above yielded 12.4 mg of 2,3-di-O-methylglucose. Determine what percentage of the glucose residues in the amylopectin contained an (α1→6) branch. (Assume that the average molecular weight of a glucose residue in amylopectin is 162 g/mol.)
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