@mbbsbaba__.dr.shu: Structure of DNA - * DNA = Deoxyribonucleic acid * It is a long polymer of deoxyribonucleotides * Repeating units = Nucleotides * DNA stores genetic information Components of DNA: * Nitrogenous base * Pentose sugar (Deoxyribose) * Phosphate group ⸻ Nucleoside Composition: * Nitrogenous base + Pentose sugar * Phosphate absent Formation: * Base joins sugar by N-glycosidic linkage * Base attached to 1′ carbon of sugar Examples: * Adenosine * Guanosine * Cytidine * Uridine * Deoxyadenosine * Deoxyguanosine * Deoxycytidine * Deoxythymidine Key point: * No phosphate = Nucleoside ⸻ Nucleotide Composition: * Nitrogenous base + Sugar + Phosphate group Formation: * Phosphate attaches to 5′ carbon * Bond formed = Phosphoester linkage Key point: * Nucleoside + Phosphate = Nucleotide * Basic building block of DNA and RNA ⸻ Polynucleotide Chain Formation * Two nucleotides join by 3′–5′ phosphodiester linkage * Product formed = Dinucleotide * Continuous joining forms Polynucleotide chain (DNA strand)

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Friday 31 July 2026 03:02:53 GMT