The cell was discovered by Robert Hooke in 1665. It is the smallest living structural and functional unit. It is a microscopic body, not visible to naked eyes. A human body is composed of trillions of cells. Bacteria can be single-celled. They are of different shapes and sizes, some of them are circular, some rectangular while some are disc-shaped. Each cell body is enclosed in a membrane and has several organelles within it. Each organelle performs a specific function. Some organelles are nucleus, golgi apparatus, mitochondria, endoplasmic reticulum, etc.
What is a Cell?
