When a segment of DNA is examined then the nucleotide in one DNA molecule, it will be expected that the sum of purine in one strand will be equal to the sum of the pyrimidine in the other strand.
Adenine combines with Thymine and Cytosine combines with Guanine in 1:1 ratio.
More specifically the ratio of purine is to pyramidine is 1:1 in an organism. This pattern is seen in both the strands of the DNA.
