because they do
In eukaryotic cells, the chromosomes are located in the nucleus. In prokaryotic cells, the chromosomes are in the cytoplasm.
Simplified version that an intro biology course would look for: Eukaryotes have multiple pairs of linear chromosomes. The gene-coding sequences are interspersed with non-coding regions that may...
Histone
Bacteria have a single circular chromosome while eukaryotes have several linear chromosomes.