Why do you think in the table below, Adenine and Thymine have almost the same number – but not exactly? Nucleotide

# found in genome

Adenine

701,234,142

Guanine

803,127,160

Cytosine

803,127,162

Thymine

701,234,146

Adenine pairs with thymine and Guanine pairs with cytosine. The numbers are not exactly the same because of the mutations that happen in DNA. Some of the DNA could be broken off or put somewhere else in the gene that would throw everything off, nothing is perfect. However in a perfect world, both adenine and thymine would have the same numbers.