Describe the structure of DNA

DNA is a nucleic acid. Nucleic acids are made up of 3 base units: a 5 carbon sugar (for DNA this is deoxyribose), a phosphate and a nitrogenous base. The phosphate group is covalently bonded to the 5th carbon atom of the deoxyribose sugar, and the nitrogenous group is covalently bonded to the sugar's 1st carbon atom. There are 4 possible nitrogenous bases, the pyrimidine bases: thymine (T); cytosine (C), and the purine bases: guanine (G); adenine (A)When the nucleic acids are joined together the phosphate attached to the 5' carbon of the deoxyribose attaches to the 3' carbon atom of the adjacent nucleotide. This creates a sugar-phosphate backbone. Pairs of bases are attracted to each other and form hydrogen bonds between them (A pairs with T by 2 hydrogen bonds, and C pairs with G by 3 hydrogen bonds). The 2 strands of DNA run anti-parallel to one another and form a double-helix structure