Robert Hooke First described cells while looking at cork Said they looked like little rooms Cell Theory Schwann contributed these 2 parts 1. All organisms are made of one or more cells. 2. The cell is the basic unit of all living things. Virchow contributed this part 3. All cells come from existing cells Prokaryotic vs. Eukaryotic Cells Prokaryotic Eukaryotic Nucleus no yes Unicellular organisms yes Yes, in some cases Multi-cellular organisms no yes Examples of organisms Bacteria & Archaea Humans, Plants Membrane covered organelles no yes Shared characteristics DNA Cell Membrane Cytoplasm Ribosomes