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Cell Nucleus ‘The Cell’s Brain

A cell's nucleus controls the activities of a cell.

Before we explore the cell’s organelles (small organs), let’s first head straight for the brain, or nucleus. A cell’s nucleus is responsible for directing the activities of the cell, in the same way that your brain directs the activities of your body.


Nuclear Membrane.A cell’s nucleus is surrounded by a thin wall, or membrane. This membrane is called the nuclear membrane, and protects the nucleus from outside dangers.Just like the cellular membrane, the nuclear membrane also has many small openings which allow things to come in and out.


Chromosomes (can you see the tiny strands of DNA?).As we travel through an opening and into the nucleus, you will begin to see many small rod-like objects called chromosomes. These chromosomes contain the blueprints for how cells and organisms should be built. The chromosomes are made from smaller molecules called DNA and RNA.


Look around. In addition to chromosomes, you will also see a small round object called the nucleolus. The word nucleolus means little nucleus. It is believed that the nucleolus is where a cell creates ribosomes, which we will talk about shortly.


A cell's nucleus controls the activities of a cell.