In his experiments on the chemistry of $DNA$,Chargaff estimated the base composition of human sperms and found that Adenine constituted $31\%$ and Guanine $19\%$. The quantity of Cytosine in the $DNA$ of human somatic cell is likely to be (in $\%$)

Explain the role of the following scientists in the discovery of the structure of $DNA$:
$1.$ Watson and Crick $(1953)$
$2.$ Erwin Chargaff

What is the number of hydrogen bonds in a $DNA$ fragment containing only $5$ guanine nitrogen bases?

The term 'gene' refers to

Read the following statements and choose the set of correct statements:
$(a)$ Euchromatin is loosely packed chromatin
$(b)$ Heterochromatin is transcriptionally active
$(c)$ Histone octamer is wrapped by negatively charged $DNA$ in nucleosome
$(d)$ Histones are rich in lysine and arginine
$(e)$ $A$ typical nucleosome contains $400 \ bp$ of $DNA$ helix
Choose the correct answer from the options given below:

The functional unit of mutation is