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106

nucleus

OLogy Series
biology
card
106

nucleus

OLogy Series
biology

The nucleus is like the remote control center of the cell. It acts as the cell's brain by telling it what to do, how to grow, and when to reproduce. The nucleus is home to the cell's genes. A membrane, a thin layer that allows chemicals to pass in and out to the rest of the cell, surrounds the nucleus.

2, then 4, then 8, then 16...
Did you know that when you started out, you were made of only ONE cell? Now, your body is made of trillions of cells. How did you go from one to trillions? Cells multiply by splitting in half. When a cell is ready to divide, it begins to make a copy of all the DNA in its nucleus. Then, just before it divides, the membrane around the nucleus dissolves and the cell pulls itself in two. Each half takes one copy of the DNA with it. New membranes build around the DNA and new nuclei form. Repeat this several trillion times and you've got you!

The nucleus helps a cell:

swim faster

grow and reproduce

see where it's going

Are you right?

Correct!

The nucleus contains a variety of chemicals and proteins, as well as the directions that it needs to grow, divide, and reproduce.

The word "nucleus" comes from the Greek meaning:

little brain

little nut

little power plant

Are you right?

Correct!

In Greek, nucleus means "little nut." Unlike a real nut, the outer protective layer of the nucleus is permeable, which means it has lots of tiny holes that let things pass back and forth through it.

All cells have a nucleus.

Fact
or
Fiction
?

Fiction

Most kinds of cells have a nucleus, but not all of them. Bacteria and red blood cells in some mammals have no nucleus, so their DNA just floats around inside the cell.

nucleus (NEW-clee-us), more than one nuclei
Shape: roundish
Found in: almost every cell
Characteristics: contains the DNA that is responsible for the unique traits that all living things have
Importance: it is the control center of the cell and the storage center for DNA

Image credits: Kelvin Chan.