What is the basic arrangement of nucleotides (sugar, phosphate and base) in DNA?

DNA is a long polymer of simple units called nucleotides, held together by a sugar phosphate backbone. Attached to each sugar molecule is a molecule of one of four bases; adenine (A), thymine (T), guanine (G) or cytosine (C), and the order of these bases on the DNA strand encodes information. In most organisms, DNA is a double-helix (or duplex molecule) consisting of two DNA strands coiled around each other, and held together by hydrogen bonds between bases. Because of the chemical nature of these bases, adenine always pairs with thymine and guanine always pairs with cytosine.