Which of the following is not found in $DNA$?

How many weak $H$-bonds are formed between the purine nitrogen base Guanine and the pyrimidine nitrogen base Cytosine?

The reason for the double helical structure of $DNA$ is the operation of

Histones are rich in

What is a gene? Explain its structure and function.

What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?