CELLS

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Cells are considered the basic units of life in part because they come in discrete and easily recognizable packages. That's because all cells are surrounded by a structure called the cell membrane.

The cell is the very smallest unit of living matter. All living things including plants and animals are made up of cells. Cells are made of atoms, which are the smallest units of matter. There are many different kinds of cells. The two kinds you are most likely to be familiar with are animal and plant cells. Some of the differences between them are that plant cells have a cell wall and chloroplasts.

Cells all have different sizes, shapes, and jobs to do.

The cells in a single organism may have different shapes, sizes, and jobs. Organisms like humans are made up of trillions of cells. There are also one-celled organisms such as euglenas, amoebas, and bacteria. Two-thirds of a cell is water, which means that two-thirds of your whole body is water. The rest is a mixture of molecules, mainly proteins, lipids and carbohydrates. Your cells turn the raw materials in