Question

What is base complementary rules,?and who proposed it?
Erwin chargaff or Watson and crick

Answer 1

The base pairing rule states that adenine pairs only with thymine and guanine pairs only with cytosine. Two hydrogen bonds form between an adenine and thymine base pair, whereas three hydrogen bonds form between a guanine and cytosine base pair.
For example, you may know that one side of the DNA strand has the sequence AGTGGACT, where A represents adenine, G represents guanine, T represents thymine and C represents cytosine.
You can determine the base sequence of the complementary strand using the complementary base pairing rule. In this case, the complementary strand would have the sequence TCACCTGA.
These relationships are often called the rules of Watson-Crickbase pairing, named after the two scientists who discovered their structural basis.