# Nucleus

This article describes an organelle, a cell component with its own distinctive structure and function. In eukaryotic cells, this is bounded by its own membrane, which is a lipid bilayer made of phospholipid.
Unless otherwise specified, information about this organelle is about its in situ occurrence in vivo, i.e., its occurrence in its usual location in living cells.

## Definition

The nucleus is an organelle found in eukaryotic cells that performs a lot of coordinating functions related to the cell, including cell compartmentalization, gene expression, and DNA replication.

## Summary

Item Value
Type of organisms whose cells contain a nucleus Eukaryotic cells only, including plant cells, animal cells, and the cells of protists and fungi.
Type of cells within the organisms that contain a nucleus Most cells; in particular, any cells that have plans to divide further (i.e., undergo another cell cycle). An exception is mature red blood cells in mammals.
Number of nuclei within cell 1 in most cases; a few types of cells such as osteoclast have more than one nucleus.
Shape The shape can vary from spherical to oblong or pear-shaped.
Size 5-10 ${\displaystyle \mu m}$ of nuclear diameter for most cells; smaller cells have correspondingly smaller nuclei; for instance, yeast cells have a nuclear diameter of 1 ${\displaystyle \mu m}$.
Location within cell Somewhere around the center of the cell, though it may not be perfectly in the middle. This location helps the nucleus perform its coordinating functions more uniformly with the cell.
Structural components Nuclear envelope, nuclear lamina, chromosomes, nucleolus, and other nuclear bodies