· DNA strands are composed of monomers called nucleotides These monomers are often referred to as bases because they contain cyclic organic bases Four different nucleotides, abbreviated A, T, C, and G, (adenine, thymine, cytosine, and guanine) are joined to form a DNA strand, with the base parts projecting inward from the backbone of the strand · The importance of DNA became clear in 1953 thanks to the work of James Watson*, Francis Crick, Maurice Wilkins and Rosalind Franklin By studying Xray diffraction patterns and building models, the scientists figured out the double helix structure of DNA a structure that enables it to carry biological information from one generation to the nextMaking a Model of DNA 5) Construct the right side of your DNA model by putting together in sequence a cytosine, thymine, guanine and adenine nucleotide 6) Complete the left side of the DNA ladder by adding complementary nucleotides or nucleotides that fit Your finished model should resemble a ladder Dna ...