Erwin Chargaff’s work on the composition of nucleic acids began in 1944. His findings, which later became known as Chargaff’s rules, detail the specific pairings that occur in double-stranded DNA molecules.%0D%0A%0D%0AAccording to one of Chargaff’s rules, a section of DNA molecule that contains 50 base pairs and has 15 adenine bases must also contain —
35 thymine bases.
This is because of Chargaff's rule stating that in double-stranded DNA, the amount of adenine always equals the amount of thymine, and the amount of guanine always equals the amount of cytosine. So, if there are 15 adenine bases in a 50 base pair section of DNA, there must be 15 thymine bases as well (since they pair with each other in DNA replication), leaving 35 base pairs for guanine and cytosine.