Survey of cellular machinery. I. All living organisms are composed of cells. A. Cells are the units of life. Plants, animals, fungi, protists, bacteria ALL are made of cells. Variation in size of cells 3.
Most multicellular organisms begin life as a single cell.
Development - the process by which a multicellular organism is produced from a single cell. Robert Brown - English botanist who discovered Brownian motion and coined the term nucleus 4. All cells come from other cells. A. Later cell discoveries 1. Louis Pasteur - French chemist who disproved spontaneous generation.