In most prokaryotes, the chromosome number is :

Most prokaryotes (bacteria and archaea) have a single circular chromosome containing their genetic material. This single chromosome resides in the nucleoid region of the cell, as prokaryotes lack a true membrane-bound nucleus. Some bacteria may also contain additional small circular DNA molecules called plasmids, but the main chromosome number is 1. This contrasts with eukaryotes, which have multiple linear chromosomes housed within a nucleus.