A ==Key Stage 3=====Meaning===Bacteria are [[unicellular|single celled]] creature. It is a [[microorganism]] s that has have no [[nucleus]], [[mitochondria]] or [[chloroplast]] but do have [[cytoplasm]], a [[cell membrane]] and a [[cell wall]]. : Singular [[Noun]]: '''Bacterium''': Plural [[Noun]]: '''Bacteria''': [[Adjective]]: '''Bacterial''' ===About Bacteria===: Bacteria can cause disease but some are important to keep us healthy.: Some Bacteria have a tail called a flagellum.