Prokaryotic cells are the smallest and simplest of cell structures. Unlike eukaryotic cells that make up complex organisms such as animals, prokaryotic cells do not have DNA histones or organelles, and they also do not require anything more than cell division to reproduce.
The word "prokaryotic" means "before a nucleus." True to this name, prokaryotic cells contain no membrane-bound nucleus or membrane bound organelles such as mitochondria, chloroplasts, or golgi apparatus. They do still have ribosomes and genetic coding, however.
The DNA found in prokaryotes is located in a loop-shaped circlet called a "plasmid." It is not formed into chromosomes like in a more complex cell and there is only one DNA molecule per cell.
Single-celled organisms such as bacteria, cynobacteria, and archaea are all examples of prokaryotic cells. While their appearances may vary from organism to organism, they all fall into one of three basic shapes: rod-shaped, spherical, or spiral shaped.
Prokaryotic cells reproduce by the asexual method of binary fission. The DNA within the cell begins to replicate and the cell grows until it is double in size. As the chromosomes begin to pull apart, a cell wall forms, separating the cell into two relatively equal halves. Eventually these halves separate and there are two complete cells.