Each chromosome consists of a single DNA double helix. Ends of the chromosome, called telomeres . The minimal requirement for a chromosome to propagate itself in a cell is to have a replication origin, two telomeres, and centromere. Replication origins are where DNA replication is initiated. Telomeres consist of repetitive sequences that reside at the end of a linear chromosome.
Telomeres protect the DNA from degradation.
Bacterial circular chromosomes lack telomeres. The chromosome is attached to the cell membrane, which provides a mechanism for its proper segregation during cell division. Plasmids are not attached and partition randomly. The organelles of eukaryotes also contain a small circular genome, which is more akin to bacterial DNA than to eukaryotic DNA . Genetic content of chromosomes Only a very small portion of a typical eukaryotic genome actually codes for anything.