Cells may exist as independent units of life, as in bacteria and protozoans, or they may form colonies or tissues, as in all plants and animals. The cell is bounded by a cell membrane , which in the cells of plants, fungi, algae, and bacteria is surrounded by a cell wall . There are two main types of cell. The nuclear material is not bounded by a membrane and chemicals involved in cell metabolism are associated with the cell membrane.
Reproduction is generally asexual and involves simple cell cleavage.
Plants and animals consist of eukaryotic cells but plant cells possess chloroplasts and other plastids and bear a rigid cellulose cell wall. Robert Brown discovers the nucleus in plant cells. Theodor Schwann states that animals are composed of cells and concludes that all living things are made up of cells. Strasburger coins the words 'cytoplasm' and 'nucleoplasm'. Camillo Golgi discovers the Golgi apparatus.