This is known as double helix. Nucleotides each have three parts: phosphate, sugar molecule<span>, and one of four </span>bases<span>. The </span>bases<span> include: A, (adenine), g (guanine), t (thymine), c (cytosine). ... </span>Explain why complementary base pairing is necessary to maintain the double helix shape of the DNA molecule<span>.</span>
