Science glossary film: Cell

The basic structural and functional unit of life. Some organisms, such as bacteria, consist of only a single cell, whereas complex organisms like humans may contain 100 trillion. Cells vary enormously in size as well as function. Most are too small to see, around one-hundredth of a millimetre in size. At the other extreme, an unfertilised ostrich egg is the heaviest single cell, weighing around 1kg.

Some organisms, such as bacteria, consist of only a single cell, whereas complex organisms like humans may contain 100 trillion. Cells vary enormously in size as well as function. Most are too small to see, around one-hundredth of a millimetre in size. At the other extreme, an unfertilised ostrich egg is the heaviest single cell, weighing around 1kg.