In the 1940s, the Austrian biochemist Erwin Chargaff (1905-2002) discovered some facts about DNA. . .
The percentage composition of nucleotides was different in different organisms.
- Human DNA contains about 29% A; octopus DNA is about 33% A, and corn DNA has about 27% A. . . etc.
BUT: the percentage of adenine (A) always equaled the percentage of thymine (T)
The percentage of guanine (G) always equaled the percentage of cytosine (C)
And %[A+G] always equaled %[T+C]
These are still called ìChargaffís rulesî