Nucleic acids are a class of macromolecules essential for the storage and transmission of hereditary information within living organisms. Chemically, they are polymers composed of monomer units called nucleotides. These nucleotides contain three components: a phosphate group, a five-carbon sugar, and a nitrogenous base. The two primary types are deoxyribonucleic acid (DNA), which typically forms the structure containing the organism's genetic blueprint, and ribonucleic acid (RNA), which plays critical roles in gene expression, such as in the assembly of proteins. The structure and chemical interactions between these acids dictate the genetic code, enabling life processes from replication to transcription.