An introduction to cells and metabolism

Model 1. The smallest unit able to sustain life is called a cell. A cell can be simply defined as a container of small and large molecules that are essential for the survival of an organism. Unicellular organisms are called prokaryotes (pronounced PRO-CARRY-OATS), and they contain all that is necessary for their survival within a single cell – bacteria are examples of prokaryotes. When cells evolved to live as a collection or group, some organisms became, by definition, multicellular; these eukaryotes (pronounced YOU-CARRY-OATS) contain many individual cells that have distinct functions – animals and plants are examples of complex organisms comprised of eukaryotic cells.