Biology
The cell
The smallest building block of life: what you, a tree, and a bacterium are all made of.
When you cut your finger, the skin grows back together. When you eat something, it turns into building blocks for your body. Behind all of this are tiny units, the cells. They are so small that you cannot see them with the naked eye: a typical cell in your body is only about 0.02 millimeters across, and it takes around 50 of them side by side to span a single millimeter. Even so, every living thing is made of them: you, your dog, every plant, and every bacterium. The cell is the smallest unit we call alive.
The most important parts
A cell is like a tiny city with different departments. The nucleus is the control center: it holds the blueprint that runs everything. The cell membrane is the border around the cell. It holds the cell together and decides what may enter and leave. The mitochondria are the power plants: they supply the energy the cell needs to work.
Control centre holding the DNA
A great many at once
A single bacterium is just one cell, and that cell has no nucleus: its blueprint lies free inside. Your body, in contrast, is made of around 30 trillion cells, and one trillion is a thousand billion. They are not all the same: muscle cells, , and skin cells look different because they have different jobs. Together they form your whole body.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
What is the smallest unit of life?
Which part is the control center of the cell?
How many cells does a bacterium need in order to live?
Match each part of the cell to its job.
State the number of parts introduced in the text as the most important ones: nucleus, membrane, and mitochondrion.
The nucleus is the control center because it holds the … that runs everything.
Where this leads