Nukleosomene

Nukleosomene, also known as nucleosome in English, are the fundamental structural units of chromatin in eukaryotic cells. They consist of a segment of DNA wound around a core of histone proteins, forming a specialized packaging system that compacts DNA within the nucleus. Each nucleosomene typically includes approximately 147 base pairs of DNA wrapped around an octamer composed of two copies each of four histone proteins: H2A, H2B, H3, and H4.

The nucleosomene serves not only as a means of DNA packaging but also plays a crucial role in gene regulation, DNA replication, and repair processes. The positioning and modification of nucleosomene influence the accessibility of genetic information, thereby impacting gene expression patterns. Histone modifications, such as methylation, acetylation, and phosphorylation, can alter the structure of nucleosomene and modulate how tightly DNA is wound, which in turn affects transcriptional activity.

Nucleosomene are arranged in a linear array along the DNA molecule, creating a "beads-on-a-string" appearance under electron microscopy. These structures can further condense into higher-order chromatin fibers, especially during cell division, culminating in the formation of chromosomes. The dynamic nature of nucleosomene allows cells to regulate DNA accessibility in response to various biological signals, making them essential for maintaining genomic stability and proper cellular function.

Overall, nukleosomene are vital for organizing eukaryotic DNA into a compact, manageable form, while also allowing for complex regulation of genetic activity.