Chromosomal crossover

Chromosomal crossover is a vital process that occurs during meiosis, a type of cell division that produces gametes in sexually reproducing organisms. This process contributes to genetic diversity by exchanging DNA between two homologous chromosomes, resulting in recombination of genetic material.

Overview

Chromosomal crossover, also known as recombination, is a natural process that occurs during the prophase I stage of meiosis. It involves the exchange of genetic material between two homologous chromosomes, which are a pair of maternal and paternal chromosomes that pair up during meiosis.

Process

The process of chromosomal crossover begins when the two homologous chromosomes pair up in a process known as synapsis. During synapsis, the chromosomes come into close contact and form a structure known as a tetrad.

Following synapsis, the chromosomes undergo a process known as crossing over. During crossing over, the two chromosomes exchange segments of their DNA. This exchange of genetic material results in the recombination of genetic material, creating new combinations of genes that were not present in the parent organisms.

Significance

Chromosomal crossover plays a crucial role in the evolution and diversity of species. By creating new combinations of genes, it contributes to the genetic variation within a population. This genetic variation is the raw material for natural selection, allowing populations to adapt to changing environments.

Chromosomal crossover also ensures the proper segregation of chromosomes during meiosis. Without crossover, homologous chromosomes may not segregate properly, leading to the production of gametes with an incorrect number of chromosomes, a condition known as aneuploidy.

See also

• Genetic recombination
• Meiosis
• Homologous recombination
• Non-homologous end joining

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  Chromosomal crossover illustration
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  Morgan crossover example 1
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  Morgan crossover example 2
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  Homologous recombination process
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  Holliday junction diagram
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  Holliday junction photograph
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  Coloured Holliday junction
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  Conversion and crossover