What are the characteristics of prokaryotic cells?

Prokaryoticcell is a unicellular organism lacking membrane-bound organelles.

Thecharacteristics of prokaryotic cells are as follows:

(i) Most of them are unicellular.

(ii) They are generally small in size. The size of a prokaryotic cellvaries from 0.5 – 5 µm.

(iii) The nuclear region of a prokaryotic cell is poorly-definedbecause of the absence of a nuclear membrane. Hence, a prokaryoticcell lacks a true nucleus.

(iv) The genetic materials of prokaryotic cells are naked. Theycontain single, circular chromosomes. In addition to the genomic DNA,they have a small, circular plasmid DNA.

(v) They have specialised membranous structures called mesosomes.Mesosomes are formed by the invagination of the cell membrane. Theseextensions help in the synthesis of the cell wall, replication ofDNA. They also help in the equal distribution of chromosomes into thedaughter cells.

(vi) Membrane-bound cell organelles such as mitochondria, plastids,and endoplasmic reticulum are absent from a prokaryotic cell.

(vii) Most prokaryotic cells contain a three-layered structure –outermost glycocalyx, middle cell wall, and the innermost plasmamembrane. This structure acts as a protective unit.

Examples of prokaryotic cells include blue green algae, bacteria,etc.