All living things are made up of tiny building blocks called ‘cells’. Cells are too small to see without a microscope. Some living things have one cell, but the human body consists of about a hundred trillion cells!
Almost all cells contain a nucleus. The nucleus is very important as it controls everything that happens inside the cell. Around the nucleus is a jelly-like substance called ‘cytoplasm’. Here, lots of chemicals are stored. Around the cytoplasm is a very thin ‘skin’ called the cell membrane? This holds the contents of the cell together and controls what enters and leaves the cell. Plants and animals have different types of cells. These cells are all designed for a particular job.
Plant cells
Plant cells are each surrounded by a ‘cell wall’ made of cellulose, which gives the plant structure and support. They each have a nucleus and cytoplasm. Plant cells usually have a very regular shape.
Animal cells
Animal cells don’t have any cell walls (just a cell membrane). This is because animals use other ways of supporting themselves, such as skeletons. Animal cells are usually irregular in shape.
Special cells have caused pigmentation in these zebras’ coats, creating a striped camouflage.
A leaf under a microscope clearly shows the structure of a plant cell.