Question

What important information was discovered about DNA in 1950 and by who?

Answer 1

In 1950, Erwin Chargaff, an American scientist, provided an experimental data which contributed significantly to the understanding of the double helical structure of DNA. This data collected from DNAs of different species are popularly known as Chargaff's rules. They are as follows:-

1. The base composition of DNA varies in different species.
2. DNA from different tissues of the same species have the same base composition.
3. The base composition of a DNA in a species does not undergo any change with the organism's age, nutritional status or changing environment.
4. In all species, the number of adenine is equal to the number of thymine residues (A=T) and the number of guanine is equal to the number of cytosine residues (G=C). Thus the sum of the purine residues is equal to the sum of pyrimidine residues (A+T= G+C).