Nucleus (Control center)
The nucleus is the control center of the cell. It is enclosed by a nuclear membrane that consists of 2 phospholipid bilayers: an inner and outer nuclear membrane that are separated by the perinuclear space. The outer membrane connects to the rough endoplasmic reticulum and is covered with ribosomes. The outer membrane called nuclear pores, which allow the transport of various proteins, RNA, or ribosomal subunits. The nucleus is filled with nucleoplasm and contains DNA combined with proteins called histones.
Nucleolus (Ribosome production factory)
A membrane-less organelle located inside the nucleus and composed of large amounts of ribosomal RNA and proteins. These two components are used to create premature ribosomal subunits, which are then shipped out of the nucleus through nuclear pores to the cytoplasm, where they form functional ribosomes.
Endoplasmic Reticulum (Protein and lipids production factory)
A network of folded membranes that extends from the nucleus throughout the cytoplasm. There are two types of endoplasmic reticulum. The rough endoplasmic reticulum is covered with ribosomes that synthesize proteins through the process of translation. These proteins are later shipped out of the rough endoplasmic reticulum to the Golgi apparatus for processing. The smooth endoplasmic reticulum, on the other hand, does not have any ribosomes attached to it and its function is to make lipids (especially lipids for cell membranes).
