step one: a monomer called a nucleotide, each nucleotide contains a sugar molecule, a phosphate molecule and four bases. (A) Adenine, (T) Thymine, (G) Guanine and (C) Cytosine
step two: the polynucleotide, a polynucleotide is the combination of two strands of nucleotides, bound together by by bases in the pattern of G to C and A to T
step three: the complimentary chains twist into a double helix shape