It is absent in $RNA$.

Which one of the following is the genetic material of bacteriophage $\phi X 174$?

What are polynucleotides made of?

$A$ $DNA$ molecule contains $10,000$ base pairs. What will be the length of this $DNA$ molecule?

Given below are two statements:
Statement $I$: In prokaryotes,the positively charged $DNA$ is held with some negatively charged proteins in a region called nucleoid.
Statement $II$: In eukaryotes,the negatively charged $DNA$ is wrapped around the positively charged histone octamer to form nucleosome.
In the light of the above statements,choose the correct answer from the options given below:

Identify $X$ and $Y$ in the given diagram of a nucleosome.