Cell (biology)

What is a Cell?

A cell is the tiny building block that makes up all living things. It is like a little room inside every plant, animal, and even tiny germs. The word "cell" comes from the Latin word for a small room.

Cells are so small that you need a microscope to see them. They have a special outer layer called a cell membrane that keeps everything inside. Inside, there is a jelly-like substance called cytoplasm. This cytoplasm holds important parts, like the nucleus, which keeps the cell's instructions.

Different Kinds of Cells

Living things can be made of just one cell or many cells. Scientists call living things with one cell single-celled and those with many cells multicellular.

There are two main types of cells:

• Prokaryotes: These are simple cells without a nucleus. They include bacteria and archaea.
• Eukaryotes: These cells have a nucleus and can be single-celled or multicellular. They include plants, animals, fungi, and some tiny creatures called protists.

How Do We Know About Cells?

Scientists first saw cells a long time ago. In 1665, Robert Hooke looked at a piece of cork under a microscope and saw tiny boxes. He named them "cells" because they looked like rooms in a monastery.

Later, other scientists learned that all living things are made of cells. They discovered that cells are the basic units of life and that new cells come from old cells. This idea is called cell theory.

Cells are amazing tiny worlds that work together to keep all living things alive and growing.