Question

Which of the following investigators was (were) responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Answer 1

Answer :Erwin Chargaff   a Biochemist

Explanation:

He formulated the base paring of double helix of DNA. He reasoned that since the percentage of four  DNA  bases are of this proportions in human;

                                  Adenine=30.9% and Thymine =29.4%;

                                  Guanine=19.9% and Cytosine =19.8%

Then,  the amount of adenine will always be equal to thymine,

And the amount of Guanine equals to cytosine based on this percentages of distribution.  

(Adenine and Guanine are large, molecule of Purines, while thymine and Cytosine are Pyrimidine)  

 

He concluded (although scientist believed, he did not explicitly stated this) that this should be the base paring patterns in DNA molecule. This is the first Chargaff Rule.

His second rule is that the DNA composition, in the relative amount of the four bases Adenine, Thymine, Cytosine and Guanine varies in proportion from one organisms to another. And this is the basis of molecular diversity.