Nukleoidu

Nukleoidu is the region within prokaryotic cells that contains the cell’s genetic material. It is not enclosed by a membrane-bound nucleus, which distinguishes it from eukaryotic nuclei. In most bacteria and archaea, the nucleoid contains a primary chromosome that is usually circular, though some species carry multiple chromosomes or plasmids as extrachromosomal DNA.

DNA in the nukleoidu is highly organized and compacted through supercoiling and binding to nucleoid-associated proteins (NAPs). Bacterial NAPs such as HU, IHF, Fis, and H-NS shape DNA, mediate bending and bridging, and influence gene expression. Topoisomerases, including DNA gyrase and topo I, regulate the level of supercoiling. In archaea, histone-like proteins may wind DNA into compact structures similar to chromatin. The nucleoid may be organized into domains or macrodomains that constrain regulatory interactions.

Function and dynamics: The nukleoidu supports essential processes such as replication and transcription. In bacteria, transcription and translation can be coupled in the nucleoid region. During growth and division, the nucleoid reorganizes to support replication and chromosome segregation, aided by NAPs and topoisomerases. Compared with the nucleus of eukaryotes, the nukleoidu lacks a surrounding membrane and is more dynamically structured. Similar nucleoid-like DNA-protein complexes exist in mitochondria and chloroplasts of eukaryotes.