crossing over

biology

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Apr. 20, 2026

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In genetics, crossing over is a crucial process that occurs during meiosis, the cell division that creates sex cells (gametes). It involves the exchange of segments between paired chromosomes, leading to the shuffling of maternal and paternal genes. This recombination introduces genetic variation into populations, ensuring that each resulting gamete is genetically unique and different from the parent cell.12

This process is vital for evolution, as the genetic variability it creates can help species adapt to changing environments and ensure their survival. While recombination is a natural and essential part of reproduction, laboratory manipulation of this process raises ethical concerns, particularly in areas like agriculture and the creation of new organisms.13

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genetics
The discovery of linked genes
…and reunion, also known as crossing over). In 1916 another student of Morgan’s, Calvin Bridges, used fruit flies with an extra chromosome to prove beyond reasonable doubt that the only way to explain the abnormal inheritance of certain genes was if they were part of the extra chromosome. American geneticist…
…and reunion, also known as crossing over). In 1916 another student of Morgan’s, Calvin Bridges, used fruit flies with an extra chromosome to prove beyond reasonable doubt that the only way to explain the abnormal inheritance of certain genes was if they were part of the extra chromosome. American geneticist…

linkage group
…of genes between chromosomes, called crossing over, usually occurs during meiosis, when the total number of chromosomes is halved.
…of genes between chromosomes, called crossing over, usually occurs during meiosis, when the total number of chromosomes is halved.

heredity
During meiosis
This exchange process, called crossing over, results in chromatids that include both paternal and maternal genes and consequently introduces new genetic combinations. The first meiotic division separates the chromosomal tetrads, with the paternal chromosome (whose chromatids now contain some maternal genes) going to one cell and the maternal chromosome…
This exchange process, called crossing over, results in chromatids that include both paternal and maternal genes and consequently introduces new genetic combinations. The first meiotic division separates the chromosomal tetrads, with the paternal chromosome (whose chromatids now contain some maternal genes) going to one cell and the maternal chromosome…

recombination
…enhanced by the phenomenon of crossing over, in which gene sequences called linkage groups are disrupted, resulting in an exchange of segments between paired chromosomes that are undergoing separation. Thus, although a normal daughter cell produced in meiosis always receives half of the genetic material contained in the parent cell…
…enhanced by the phenomenon of crossing over, in which gene sequences called linkage groups are disrupted, resulting in an exchange of segments between paired chromosomes that are undergoing separation. Thus, although a normal daughter cell produced in meiosis always receives half of the genetic material contained in the parent cell…