A TEXT BOOK OF MOLECULAR BIOLOGY has been designed to acquaint students with molecular techniques and to apprise them with the importance of molecular basis in our daily life. The book covers a wide spectrum of exercises designed for students comprises of Molecular basis of life includes origin of organic molecules and biomolecules and the particular experiments in chapter 1. Chapter 2, The Nucleic acids I,e. DNA & RNA A brief description and Invention with all relevant experiments. Next the chapter 3, DNA Replication deals with Types of replication, Enzymes involved and replication methods etc. DNA Repair includes types of repair, brief description with mechanism and its importance is discussed in chapter 4.The Recombination in prokaryotes deals with mechanism, types, variations and experimental pathway included in chapter 5.The Genetic code: Discovery, codon, sequence frame, mutations, salient features, variations and predictions of genetic code discussed in chapter 6.Next, Chapter 7, The Transcription in prokaryotes and Eukaryotes: Transcription of Prokaryotes by explaining Bacteria as an example I.e. Bacterial transcription, transcription factors, Enzymology and Method of Transcription and Eukaryotic transcription explained by the steps involved, methodology, enzymes involved, gene specifying etc. discussed elaborately in chapter 7. Chapter 8, Translation, the steps involved and methodology of translation. Regulation of Gene expression involves the two types of regulation I.e. Prokaryotic and Eukaryotic gene regulation with stages structure, gene regulation in developmental biology discussed in chapter 9. Gene organization and expression deals with organization and expression of gene in prokaryotes and eukaryotes involves genome compactness, sequence analysis, transcription territories and effects of gene regulation with examples explained in chapter 10. Chapter 11 The Transposons deals with Discovery, classification, types, evolution, examples and applications