REGNVM PROKARYOTAE

P rokaryotes: unicellular microorganisms of 0.1-15 μm,
presenting rod or coccus shape, sometimes occuring filamentous
or mycelial forms. They are widely distributed in nature (soil,
water, foods, plants, animals, rarely hot springs or radioactive
medium).

Cells have a single circular DNA chromosome, contained within a
region called the nucleoid and may also have various small
circular pieces of DNA (plasmids) inside the cell. The
nucleoplasm is not separated from the cytoplasm by a nuclear
membrane. Reproduction is most often asexual, through binary
fission, occasionally by budding. Cells may remain attached after
division resulting specific arrangements (strepto-, staphylo- etc.).

The cells are surrounded by a rigid peptidoglicans based wall with
the exception of the Mollicutes. The plasma membrane forms
vesicular, lamellar or tubular intrusions into the cytoplasm.
Respiratory and photosyntetic functions are associated with the
plasma membrane system (where available).
Ribosomes of the 70S type are dispersed in the cytoplasm.

Kingdom Prokaryotae includes Cyanobacteria (blue-green algae)
and Bacteria. The last makes the object of our pages.