“Atomic structure of the the larger subunit of the ribosome of prokaryotes, from Haloarcula marismortui. Proteins are shown in blue and the two RNA chains in orange and yellow. The small patch of green in the center of the subunit is the active site
A structural diagram of a bacterium. Bacteria are one domain of prokaryote, a single-celled organism which lacks a membrane-bound nucleus (karyon), mitochondria, or any other membrane-bound organelles.