DNA is made up of three subunits: a deoxyribose 5 carbon sugar, a phosphorous group, and a nitrogenous base (adenine, thymine, guanine, cytosine). All in all, these are called nucleotides that wrap around in a double helix in order to form DNA.
In living organisms DNA<span> does not </span>usually<span> exist as a single molecule, but ...... Levene suggested that </span>DNA<span>consisted of </span>a string of nucleotide<span> units</span>
