Explain why the nucleus is considered the central point of all activities of the cell.

(N/A) $ \Rightarrow $ The nucleus as a cell organelle was first described by Robert Brown in $1831$. Later, the material of the nucleus stained by basic dyes was given the name chromatin by Flemming.
$ \Rightarrow $ The interphase nucleus contains highly extended and elaborate nucleoprotein fibres called chromatin, nuclear matrix, and one or more spherical bodies called nucleoli.
$ \Rightarrow $ The nuclear envelope consists of two parallel membranes with a space between them ($10$ to $50 \, nm$) called the perinuclear space. This forms a barrier between the materials present inside the nucleus and the cytoplasm.
$ \Rightarrow $ The outer membrane usually remains continuous with the endoplasmic reticulum and also bears ribosomes on its surface.
$ \Rightarrow $ At a number of places, the nuclear envelope is interrupted by minute pores, which are formed by the fusion of its two membranes. These nuclear pores are the passages through which the movement of $RNA$ and protein molecules takes place in both directions between the nucleus and the cytoplasm.
$ \Rightarrow $ Nucleoli: These are spherical structures present in the nucleoplasm. The content of the nucleolus is continuous with the rest of the nucleoplasm. It is a site for active ribosomal $RNA$ synthesis. Large and more numerous nucleoli are present in cells actively carrying out protein synthesis.