Learning Objectives Understand the components and chemical structure of nucleotides, and their role in forming DNA and RNA molecules. Analyze the principles of base pairing and hydrogen bonding in nucleic acids, and how they contribute to the stability and specificity of DNA and RNA structures. Examine the chemical mechanisms involved in nucleic acid synthesis (polymerization) and degradation (hydrolysis), and the enzymatic processes of DNA replication, RNA transcription, and repair. Explore the different conformations of nucleic acids, including their impact on function and interactions with other molecules. Learn about analytical techniques used to study nucleic acids, and how they provide insights into structure, function, and interactions. Nucleic acids are biopolymers found in all living organisms, serving as the essential molecules for the storage, transmission, and expression of genetic information. These complex macromolecules are composed of repeating units called nucleotides, which consist of three main components: a nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and a phosphate group. There are two primary types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic blueprint of an organism, encoding the instructions for the synthesis of proteins and the regulation of cellular activities. It exists in the form of a double helix, with two complementary strands held together by hydrogen bonds between the nitrogenous bases adenine (A) and thymine (T), and guanine (G) and cytosine (C). RNA, on the other hand, plays diverse roles in gene expression, including messenger RNA (mRNA) which carries genetic information from DNA to the ribosomes for protein synthesis, transfer RNA (tRNA) which brings amino acids to the ribosomes during protein synthesis, and ribosomal RNA (rRNA) which forms the structural and catalytic core of ribosomes. The structure and function of nucleic acids are intricately linked. The sequence of nitrogenous bases along the nucleic acid chain determines the genetic code, with each triplet of bases (codon) encoding a specific amino acid or serving as a signal for regulatory functions. The ability of nucleic acids to undergo replication, transcription, and translation enables the faithful transmission and expression of genetic information from one generation to the next. Beyond their role in genetics, nucleic acids also participate in various cellular processes, including DNA repair, RNA processing, and gene regulation. Moreover, advances in biotechnology have led to the manipulation and engineering of nucleic acids for applications such as genetic engineering, molecular diagnostics, and gene therapy.