Cells: Cells are the basic unit of life.
Cell Theory: The Cell Theory states that: a) All organisms are made up of one or more cells and the products of those cells b) All cells carry out life activities, require energy, grow and have a limited size c) New cells arise only from other living cells by the process of cell division
Animal Cells: Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall.
Size of cells: Most cells, both animal and plant, range in size between 1 and 100 micrometers and are thus visible only with the aid of a microscope.