Final answer:
Prokaryotic chromosomes, which are circular in structure, lack histone proteins and the heterochromatin that eukaryotic chromosomes have.
Step-by-step explanation:
Prokaryotes, such as bacteria and archaea, have chromosomes that are circular in structure, not linear like those in eukaryotes. One feature that such chromosomes lack is organization around histone proteins. Unlike eukaryotes, prokaryotic chromosomes do not form complex structures with histones to create heterochromatin. Therefore, prokaryotic chromosomes would lack both histones and the heterochromatin that results from the interaction between DNA and histones in eukaryotic cells. While prokaryotes condense their DNA by supercoiling, aided by DNA gyrase, eukaryotes wrap their DNA around histone proteins to pack their chromosomes.
Prokaryotes have a single, circular chromosome, which lacks histone proteins that form heterochromatin, unlike eukaryotes. Eukaryotes, on the other hand, have multiple, linear chromosomes that are wrapped around histone proteins. The circular structure of prokaryotic chromosomes allows for efficient DNA replication and gene transfer.