Nucleic

Nucleic refers to nucleic acids, a class of biopolymers essential to all known forms of life. The two primary nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids are built from units called nucleotides, each containing a sugar, a phosphate group, and a nitrogenous base.

In DNA, the sugar is deoxyribose and the bases are adenine, cytosine, guanine, and thymine; in RNA, ribose, and adenine, cytosine, guanine, and uracil. Nucleic acids are linked by phosphodiester bonds that form a sugar-phosphate backbone. DNA typically exists as a double helix with two antiparallel strands; RNA is usually single-stranded and can fold into complex structures.

Functions: DNA stores genetic information and is replicated during cell division; transcription produces RNA; translation uses messenger RNA to synthesize proteins. RNA molecules also perform structural, catalytic, and regulatory roles (rRNA, tRNA, miRNA, etc.).

Biological context: In eukaryotes, DNA resides primarily in the nucleus, with mitochondria and chloroplasts containing their own genomes. RNA is synthesized in the nucleus and exported to the cytoplasm.

History: Nucleic acids were first identified by Friedrich Miescher in 1869 as 'nuclein'. The term 'nucleic acid' and the recognition of DNA as genetic material emerged in the mid-20th century, with Chargaff's rules and the discovery of the double-helix structure by Watson and Crick in 1953.