DNA carries genetic information in all living cells. Its chemical name is deoxyribonucleic acid, and its sequence stores the instructions used to build, maintain, and reproduce an organism.
DNA is made from four bases—adenine, thymine, cytosine, and guanine—arranged along two complementary strands. Adenine pairs with thymine, while cytosine pairs with guanine. This pairing allows DNA to be copied accurately when cells divide. Specific stretches of DNA called genes help direct the production of proteins or functional RNA molecules.
In eukaryotic cells, most DNA is packed into chromosomes inside the nucleus. Additional DNA occurs in mitochondria, and plants and algae also contain DNA in chloroplasts. Bacteria lack a nucleus but still store their genomes as DNA in the nucleoid region and often in plasmids.
RNA can also carry genetic information in some viruses, which is why the wording “all living cells” matters. RNA has crucial roles in gene expression, but DNA is the hereditary material used by cellular life. Lipids and proteins perform essential biological functions but do not serve as the universal genetic archive.