This book contains basic of molecular biology i.e from discovery of nucleic acids to the latest molecular biology. The chemical properties of nucleic acid, types structure, functions of DNA-RNA, replication, transcription, translation, post translation modifications, etc. are discussed in details. The content and images are of excellent quality to understand, study, remembering various topics u to great extent. This is at the base of 9 standard to post- graduate level book for all international students.