Kingdoms and Domains
Superkingdomprokarya
Lynn Margulis University of Massachusetts at Amherst
Michael J Chapman Marine Biological Laboratory Woods Hole, Massachusetts, USA
Publisher Summary
Members of prokarya super kingdom are single membrane–bounded genetic systems composed of prokaryotic cells that contain genophores, often visible as nucleoids by electron microscopy. Protein synthesis in this superkingdom occurs on 16S rRNA-28S rRNA two-component small ribosomes and only DNA-level unidirectional recombination is present. There is no cell fusion and lack of nuclear and cytoplasmic fusion implies non-Mendelian genetics. Unidirectional gene transfer occurs by conjugation and various forms of small genome transfer. Microscopic observation reveals that they lack visible intracellular motility, and reproduction takes place through binary fission, budding, budding of filaments, fission of stalked sessile parent to produce flagellated offspring, polar (end-to-end) growth, or multiple fission. Propagules include resistant spores, motile filaments, cystic forms, and radiation resistant walled cells.