Adenine, guanine, thymine and cytosine are the four nitrogenous bases that are attached to a sugar molecule<span> on each </span>side of the ladder<span>. When a phosphate, a sugar and a base form an attachment, they create a sub-unit of </span>DNA<span> called a nucleotide. Each nitrogenous base is held together by a hydrogen bond.</span>
Oxygen and hydrogen make up water
