Which one of the following histone is not present in the core particle of nucleosome
$H_1$
$H_2$
$H_3$
$H_4$
The haploid content of human $DNA$ is
Which one of the following pair is a purine pair?
The two strands of $DNA$ are held together by
Which of the following is not correct
Distinguish between heterochromatin and euchromatin. Which of the two is transcription-ally active ?