When a cell copies its dna (replication), the original dna ladder is broken apart and new nucleotides are added to the center. this creates two exact copies, each one made from half the original dna molecule. • dna polymerase (the enzyme which builds dna) will only attach bases which match with the original strand of dna. • in dna replication, adenine and thymine will bong together and cytosine and guanine will bond together. • when creating the matching stand the following pairing rules must be used: a? t c? g directions: use the base pairing rules above to figure out the sequence of the new strand of dna for the original strands below. 1. 2. 3. 4. 5.