Summary
Highlights
The nucleus's primary function is to contain the cell's genetic material. It is surrounded by two separate membranes: an outer and an inner membrane.
The outer and inner membranes separate the nucleus from the cytoplasm. Inside the nucleus is the nucleoplasm, a distinct fluid from the cytoplasm. Transport between these two compartments is essential for cellular functions.
Transport of molecules like mRNA out of the nucleus and proteins into the nucleus occurs through nuclear pores. These pores span both membranes and are highly selective, recognizing specific signals to regulate what enters and exits the nucleus.
A densely compacted area within the nucleus is called the nucleolus, which is the site of ribosome assembly. It contains regions of DNA that produce ribosomal RNA, which then combines with proteins to form ribosomes. These ribosomes are then trafficked out to the cytoplasm.
The outer nuclear membrane is continuous with the membranes of the endoplasmic reticulum. The nuclear envelope refers to the combination of the inner and outer membranes along with the nuclear pores, enclosing the nucleus.