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What is a Cell?

Cells are the building blocks that create life.  Ever wondered what makes up your skin, organs or muscles? Fasten your seatbelts. You are about to see a world that is all around you, and yet so small that you probably have never seen it. What is this world? It is the world inside your body and inside the bodies of all living things. It is the world of the cell.  So, what is a cell?


Well, cells are like little factories inside of all living things that have a specific job. This job differs from cell to cell.  For instance, nerve cells work together to help us think or move, whereas a blood cells help carry oxygen to our organs and muscles.

Cells build up almost everything around you, including you!  As a matter of fact, they build up every living thing on Earth from the squirrels in your backyard to the trees they scurry up.  In fact, living things are considered “living” because cells themselves are living.  They are like these little units in our body that give us life.

Moreover, individual cells are even considered living things such as a bacteria cell.  So when we talk about living things, we could be talking about one single cell or about a complex system of cells that work together to create something larger, like you!

In our bodies alone, there is thought to be around 37 trillion cells.  These cells work together to create things that we need to help us live.  In other words, cells like little factories inside your body working each day to create biological equipment to keep you alive, or any living thing alive.

Image of a cartoon animal cell

Cartoon animal cell with cell organelles

How big are cells?

Cells range in size. From the largest, which are about the size of a period at the end of this sentence, to the smallest, which are so tiny they can only be seen with very powerful microscopes.

A couple of exceptionally large cells exist. One example is the yoke of an egg which is actually a very large cell.  So, next time you are about to dig into a large fried egg, you are actually about to dig into an extremely large fried cell. Yum!

Types of Cells

Thousands of different cells exist here on Earth.   In fact, cells are unique for each living thing. These cells can be broken up into two main categories: prokaryotic cells and eukaryotic cells.  Prokaryotic cells have nuclei which are not bound by a membrane.  Whereas, eukaryotic cells have nuclei which are bound by a membrane.

Moreover, eukaryotic cells are further grouped into two categories: animal cells and plant cells.  Cells that form us and the animals around us are animal cells. Whereas, cells that make the leaves on a tree or the petals on a flower are called plant cells.

What’s inside a cell?

Inside a cell are tiny organs called cell organelles. In fact, the word organelle is just a big word which means small organ. These organelles are responsible for providing all the needs of the cell. They work to bring in food supplies, get rid of waste, protect the cell, repair the cell, and help it grow and reproduce.

Organelles in a cell are much like organs in our body.  Each one has a specific job to complete for the cell. And, if one organelle within the cell stops completing its job, then the cell will die.


Written by: Lauren Lacey