Bacteria are amongst the simplest of organisms – they are made of single cells. Their cell structure is simpler than the cells of animals, plants and fungi.

single-celled organisms that have a relatively simple structure. Prokaryotic cells are surrounded by a plasma membrane, but they have no internal membrane-bound organelles within their cytoplasm.

Planctomycetes challenge our concept of the bacterial cell and of a prokaryote as a cell structure type, as well as our ideas about origins of the eukaryote nucleus. Planctomycetes Are Important ...