Crossing over
Crossing Over
Crossing over (pronunciation: /ˈkrɔːsɪŋ ˈəʊvər/), also known as recombination, is a significant process in genetics that occurs during meiosis. The term is derived from the Latin words "crux" meaning "cross" and "over" meaning "beyond".
Definition
Crossing over is a process where homologous chromosomes pair up and exchange segments of their DNA during the first division of meiosis. This results in new combinations of genes, which can lead to genetic variation in offspring.
Process
During the early stages of meiosis, homologous chromosomes come together in a process known as synapsis. At this point, the chromosomes can break and rejoin, swapping sections of DNA. This is the physical process of crossing over. The points at which these exchanges occur are called chiasmata.
Significance
Crossing over is crucial for the generation of genetic diversity, which is a key factor in evolution. By creating new combinations of genes, crossing over contributes to the variation upon which natural selection can act.
Related Terms
- Genetics: The study of genes, genetic variation, and heredity in living organisms.
- Meiosis: A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell.
- Homologous chromosomes: Chromosomes in a biological cell that pair up during meiosis.
- Synapsis: The pairing of two homologous chromosomes that occurs during meiosis.
- Chiasmata: The point where two homologous chromosomes remain in contact during meiosis and where exchange of genetic material occurs.
External links
- Medical encyclopedia article on Crossing over
- Wikipedia's article - Crossing over
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