This document discusses the structure and function of cells. It outlines the cell theory, which states that all living things are made of cells, cells are the basic functional units of life, and new cells are produced from existing cells. The document then describes the key components of cells, including the cell membrane, nucleus, cytoplasm, mitochondria and various organelles. It explains that cells come in two main types - prokaryotic and eukaryotic - and provides examples of different cell types.