Bacterial chromosome

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As bacterial chromosome the largest are DNA molecules of a bacterium designated, the next smaller DNA molecules, the plasmids in the cell occur.

These so-called chromosomes of bacteria differ fundamentally from a chromosome in the classic sense that occurs in eukaryotes . The bacterial carrier of hereditary information is often more than 1 mm long DNA , most of which is not present as a linear double strand, but as a closed circular molecule, individually or in a few copies. The ring molecule, lying freely in the cytoplasm , occupies a non-membrane-covered area of ​​the bacterial cell, which is called a nucleoid or nuclear equivalent . It is associated with proteins and is spatially structured. But as with all prokaryotes , the chromosomal material of the bacteria does not contain any chromatin . The DNA is compressed as a result of internal ring tension by a twist, which is called supercoiling here , while the chromosome in the eukaryotic cell nucleus is packed several times by chromatin.

In most prokaryotes, the DNA is circular, which means that replication is possible without the formation of telomeres . There are only a few types of bacteria with linear chromosomes, for example Borrelia and Streptomycetes .

Many eukaryotes , including plants and animals, have organelles such as mitochondria and chloroplasts that contain circular DNA. These organelles are very similar to real prokaryotes (see also endosymbiont theory ).

Analogous to the genome of the eukaryotes , the entirety of the DNA of a prokaryotic cell, and also that of viruses, is sometimes called a genophore ; however, this expression has not yet caught on.

Web links

Wiktionary: bacterial chromosome  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ H. Ris: Ultrastructure and molecular organization of genetic systems. In: Can. J. Genet. Cytol. Vol. 3, 1961, pp. 95-120.
  2. ↑ Benham C, Mielke S: DNA mechanics . In: Annu. Rev. Biomed. Closely. . 7, August, pp. 21-53. PMID 16004565 .
  3. ^ A b D. Nelson, M. Cox: Principles of Biochemistry. Third Edition 2000, ISBN 1-57259-153-6 , pp. 28-39.
  4. ↑ Matthias Redenbach, Josef Altenbuchner: Why do some bacteria have linear chromosomes and plasmids? In: Biospectrum. Vol. 8, No. 2, 2002, pp. 158-163. PDF .
  5. ^ Biology Glossary
  6. ^ Lynn Margulis: Hans Ris (1914-2004). Genophores, chromosomes and the bacterial origin of chloroplasts. In: International Microbiology. Volume 8, 2005, pp. 145-148.