DNA and RNA — Prelims Strategy

Prelims Strategy

To excel in NEET questions on DNA and RNA, a multi-faceted strategy is essential. Firstly, master the basic chemical structures: clearly differentiate between ribose and deoxyribose sugars (especially the 2'-OH group), identify the five nitrogenous bases (purines vs.

pyrimidines, T vs. U), and understand the components of a nucleoside versus a nucleotide. Secondly, understand the bonding: know where glycosidic bonds, phosphodiester bonds, and hydrogen bonds are located and their respective strengths.

Phosphodiester bonds form the backbone, while hydrogen bonds stabilize the double helix. Thirdly, memorize Chargaff's rules for double-stranded DNA (A=T, G=C) and practice numerical problems based on these rules.

Fourthly, differentiate DNA and RNA based on sugar, bases, strandedness, and stability. Finally, for RNA, be familiar with the different types (mRNA, tRNA, rRNA) and their specific functions. Pay close attention to keywords like 'deoxy', 'ribo', 'nucleoside', 'nucleotide', 'double-stranded', 'single-stranded' in the questions.

For numerical problems, write down the given values and apply the correct formula (Chargaff's rules) systematically.