They are very complex compounds being created by the atomic linking of thousands of individual atoms. DNA or deoxyribonucleic acid , the genetic blueprint of life, is an example of a nucleic acid. All organisms are composed of one or more of cells . Cells are the smallest self-functioning unit found in living organisms. Cells are also where the processes of metabolism and heredity occur in an organism.
Cells arise by the cellular division of a previously existing cell.
Biologists have differentiated two basic types of cells in organisms. Bacteria , archaea , and cyanobacteria have cells that are quite uncomplicated in terms of structure and function. Quite simply, they lack internal organization. Typical prokaryote cell. These cells are about 1 to 10 micrometers in size.