What is a cell?
Not a cell phone. Not a prison cell. What do we mean when we talk about cells in science?
At Centre of the Cell we love to say that ‘cells are the building blocks of life’. Just like a builder would make a house, or you might construct something from lego, if you wanted to build a real life animal, or a real life plant, you’d need lots and lots of cells to stack up one on top of the other. Cells are so small that – unlike the bricks of a house – we can’t even see them with the naked eye. Trust me though, they’re definitely there! By looking through a microscope (like a telescope but for seeing really tiny things) scientists can see cells, and that’s how we found out about them in the first place.
The truth is though, cells are even more incredible than building blocks. Unlike bricks, cells actually do things, like tiny machines working inside our body. Some cells are in charge of helping us move (muscle cells), some send signals across our body like little wires (nerve cells), and some carry oxygen around in our blood (red blood cells). That’s not all either: bone cells, skin cells, liver cells – the list goes on and on. If you’re wondering, there are actually around 260 different types of cell in a human body, far too many to list here!
How do we get so many cells?
It turns out that at one point (when you first started growing inside your mother’s tummy) you used to be only one cell big. Smaller than a grain of sand! From there, your cell did an incredible thing and split itself up into two equal pieces. Now you’re two cells big. What next? They split again – suddenly you’re four cells big. You can see where this is going. All through your life your cells kept splitting up over and over until you were as big as you are today. Scientists call this splitting mitosis (my-toe-sis), and almost every single cell in the world does it.
The reason why we love cells so much is because there would be no life in the entire universe without them. Scientists believe that the first forms of life that ever existed were just one cell big for their whole life – like a bacteria or an amoeba. Nowadays cells don’t work alone – whether it’s in a tree, a jellyfish or a horse, cells all work together to keep their organism alive day and night. For example, an adult blue whale has about 10 quadrillion cells (10,000,000,000,000,000 cells), all of them working together to help it survive. By comparison, we humans have 50-100 trillion cells depending on how big you are. As a general rule, the bigger the animal, the more cells you have.
Why learn about cells?
Learning about cells helps scientists solve the big problems in medicine today like cancer, diabetes and infections (such as coronavirus). Cell science is even used to help us grow more food by helping plant cells grow faster and stopping them from getting diseases – yes plants can get diseases too! Who knows what problems might be solved in the future by cell science? The sky is the limit.