Each nucleotide consists of three parts. These three parts can be represented diagrammatically, as shown below. Name and briefly describe the key chemical features for each of the '3-parts' of a nucleotide represented by each shape (circle, pentagon, rectangle)? [4 marks]
Write maximum 10-15 line response. 1 mark for correct name of all three parts; and 1 mark x 3 for each of the three descriptions.
A nucleotide has three components - nitrogenous base, a pentose sugar ribose in case of RNA and deoxyribose for DNA) and a phosphate group. There are two types of nitrogenous bases - Purines (Adenine and Guanine) and Pyrimidines (Cytosine and Thymine).
A nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage to form a nucleoside.
When a phosphate group is linked to 5 -OH of a nucleoside through phosphodiester linkage, a corresponding nucleotide is formed. The nucleotides are linked through 3-5 phosphodiester linkage to form a dinucleotide.