CELLS - AN INTRODUCTION

Cells
Cells are very small. They are the basic building blocks of all animals and plants. 

Animal cells usually have an irregular shape, and plant cells usually have a regular shape

Cells are made up of different parts. It is easier to explain what these parts are by using diagrams like the ones below.

Animal cells and plant cells both contain:

• cell membrane, cytoplasm, nucleus

Plant cells also contain these parts, not found in animal cells:

• chloroplasts, vacuole, cell wall

The table summarises the functions of these parts.

Part	Function	Found in
Cell membrane	Controls what substances can get into and out of the cell.	Plant and animal cells
Cytoplasm	Jelly-like substance, where chemical reactions happen. In plant cells there's a thin lining, whereas in animal cells most of the cell is cytoplasm.	Plant and animal cells
Nucleus	Controls what happens inside the cell. Carries genetic information. In exams don't call the nucleus the 'brain' of the cell. That is not a good description and will not get you marks.	Plant and animal cells
Chloroplast	Where photosynthesis happens – chloroplasts contain a green substance called chlorophyll.	Plant cells only
Vacuole	Contains a liquid called cell sap, which keeps the cell firm.	Plant cells only
Cell wall	Made of a tough substance called cellulose, which supports the cell.	Plant cells only

From: BBC BiteSize