rekombination

Rekombination refers to processes in which components that were previously separated combine to form a larger, more stable, or differently organized product. The term is used across disciplines, including biology, chemistry, plasma physics, and cosmology, often with domain-specific meanings but sharing the core idea of rearrangement or pairing of constituents.

In biology and genetics, DNA recombination describes the exchange or rearrangement of genetic material. Mechanisms include homologous recombination, which uses shared sequences to align DNA strands, and non-homologous end joining, which ligates ends without extensive homology. Site-specific recombination uses defined sequences for targeted rearrangements. Recombination creates genetic diversity during meiosis and participates in DNA repair and genome maintenance.

In the immune system, somatic recombination of antigen receptor genes (for example, immunoglobulin and T-cell receptor loci) generates diverse receptors essential for recognizing a wide range of pathogens.

In physics and cosmology, recombination describes the capture of free electrons by ions to form neutral atoms in a plasma. Radiative and dielectronic recombination contribute to the charge balance in astrophysical plasmas. The cosmological epoch of recombination, about 380,000 years after the Big Bang, marks the formation of neutral hydrogen and the decoupling of photons, which forms the cosmic microwave background.

In chemistry and materials science, recombination can refer to the pairing of radicals to form stable molecules or to electron-hole recombination in semiconductors. The latter governs the efficiency of devices such as light-emitting diodes and solar cells, with radiative recombination emitting photons and nonradiative pathways reducing performance.