The nucleoid contains a circular, single, large DNA molecule. This DNA molecules in bacteria ranges in size from about 250 to 1500 micrometers. Very little is known about the makeup and structure of the DNA in cyanobacteria, but we do know that there is substantially more DNA in cyanobacteria as compared to bacteria, but the structure is unknown. According to study, it seems as if the cytoplasm is very dense around the nucleoid, which is mainly due to the presence of a large number of small spherical particles called ribosomes, which assemble amino acids into proteins. Ribosomes consist of over 50 different proteins as well as a few types of RNA, or ribonucleic acid.
Some prokaryotes have a much more complex structure than others.
Some contain vesicles or vacuoles, which are closed bag-like sac. Many bacteria can move rapidly by use of their flagella, which is a chain of long threadlike protein molecules connected to the cell. Although these prokaryotes seem very simplistic in structure, they actually can be quite complex. They contain complex molecular systems, use a variety of substances for energy, and in many ways are more versatile in their activities than are the more-complex eukaryotic cells. Eukaryotes is derived from the roots eu meaning typical, and karyon meaning nucleus.