In the prokaryotes such as bacteria, the genetic system or the genetic material consists of a single circular chromosome made up of DNA. Due to the absence of a nucleus in prokaryotes, the genetic material is not present inside the nucleus.
Unlike eukaryotic DNA that binds with basic proteins histones (H2A, H2B, H3, H4, and H1) to form a structure known as nucleosome, the prokaryotic DNA lacks histone proteins (except the domain Archaea).
The main function of histone is to package the eukaryotic DNA in a smaller space. In the prokaryotes, they package their DNA in a small space by supercoiling.