Cells can be organism or it can compose organisms. There are 2 types of organisms: unicellular organisms: perform all function in a single cell. Ex: bacteria or protists: multicellular organisms: have specialized compartments that perform different functions. However, the cells have the same basic structure. Cell theory states that: cells are the basic unit of life, cells come from other cells. Plasma membrane: separated the internal and external environment. Dna: stores genetic information to pass to the next generation. Ribosomes: build proteins that are the building blocks of life. Cytoplasm: is where the biochemical processes take place. Virchow in 1858 believed that the study of cells was necessary to understand pathology. Prokaryotic cells are simple, unicellular organisms that lacks a discrete nucleus surrounded by a nuclear membrane. Their genetic materials are contained within a single chromosome. Eukaryotic cells include protists [unicellular] and fungi, animals, and plants.