the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic. Cells are only visible under a microscope.
Range in size between 1 and 100 micrometers
Lack of rigid cell wall helps develop diverse tissues and organs.
most animal tissues are bound together in an extracellular matrix.