Author: Ms. Pushplata Kanwar
Volume: 01
First Online: 2026
Pages: 1-73
DOI:

This chapter provides a comprehensive overview of chromosomes and nucleic acids, emphasizing their structural organization, biological functions, and significance in heredity, gene regulation, and molecular biology. It begins with the structure and classification of chromosomes, including chromatin organization, nucleosomes, the solenoid model, and differences between prokaryotic and eukaryotic chromosomes. The chapter further explains chromosome morphology, centromere-based classification, sex chromosomes, autosomes, supernumerary chromosomes, and specialized chromosome types. It discusses the role of histone proteins and their post-translational modifications in chromatin remodeling and epigenetic regulation. The structural and functional aspects of DNA and RNA are presented in detail, including nucleotide composition, the Watson–Crick model of DNA, alternative DNA conformations (A-, B-, and Z-DNA), plasmid DNA, genomic DNA, repetitive DNA, DNA polymorphisms, and epigenetic modifications. In addition, the chapter describes the diverse classes of RNA, RNA interference mechanisms, CRISPR-Cas genome editing technology, and the molecular basis of mutations and chromosomal aberrations. Overall, the chapter establishes a strong foundation for understanding genome organization, gene regulation, molecular genetics, biotechnology, and modern biomedical research.