Page 12 - The Cell and Its Components

Organelle
The nucleus is an organelle within the cell. This means it
has a special function and is surrounded by a membrane
that protects it from the rest of the cell. It floats within the
cytoplasm (the fluid inside the cell).

How many nuclei are in a cell?
Most cells only have one nucleus. It would get confusing
if there were two brains! However, there are some cells
that develop with more than one nucleus. It's not
common, but it does happen.

Nucleus Structure
 Nuclear envelope - The nuclear envelope is made
up of two separate membranes: the outer
membrane and the inner membrane. The
envelope protects the nucleus from the rest of the
cytoplasm in the cell and keeps the special
molecules within the nucleus from getting out.
 Nucleolus - The nucleolus is a large structure in
the nucleus that mainly makes ribosomes and
RNA.
 Nucleoplasm - The nucleoplasm is the liquid that
fills the inside of the nucleus.
 Chromatin - Chromatin are composed of proteins
and DNA. They organize into chromosomes prior
to the cell dividing.
 Pore - The pores are small channels through the
nuclear envelope. They allow for smaller
molecules to pass through such as messenger
RNA molecules, but keep larger DNA molecules
inside the nucleus.