Linkage vs Crossing Over
Linkage and crossing over are two different but inter-related genetic events in Eukaryotic organisms.
Genetic Linkage: The tendency of genes (DNA sequences) to stay together in a chromosome is called genetic linkage. The genes linked together in a chromosome are called the Linkage Group. The linkage group is equivalent to a chromosome. Thus, due to the linkage, the genes present in a particular chromosome will inherit together when the gametes are formed. The genetic linkage is compromised by the Crossing Over.
Crossing Over: The exchange of genetic material between the non-sister chromatids of a homologous chromosome is called crossing over. Crossing over is the tendency of genes to stay apart and inherit separately when the cell produces gametes. Crossing over is a natural genetic recombination process occurs during the pachytene stage of the prophase I of Meiosis.
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The process of genetic linkage and crossing over are related to each other. When the linkage between two genes increases, the chance of crossing over between these two are reduced and vice versa. Linkage and crossing over are considered as one of the most important exceptions in Mendel’s low of Independent Assortment. The present post describes the Difference between Genetic Linkage and Crossing over with Comparison Table.
Difference between Linkage and Crossing Over
Sl. No. Genetic Linkage Crossing Over 1 Linkage ensures to keep the genes in a chromosome to inherit together. Crossing over facilitates the separation of genes present in a chromosome and segregate into different gametes. 2 The strength of linkage between two genes is inversely proportional to the distance between them in the chromosome. The chance of crossing over between two genes is directly proportional to the distance between them in the chromosome. 3 The strength of linkage between two genes increases with the decrease in distance between them. The chance of crossing over between two genes decreases with the decrease in distance between them. 4 The strength of linkage decreases with increase in distance between the genes. The chance of crossing increases with increase in distance between the genes. 5 Linkage ensures the maintenance of parental trait in the offspring. The crossing over causes alternations in the parental traits in the offspring. 6 Linkage reduces the chance of creation of variability with sexual reproduction. Crossing over increases the chance of creation of variability with sexual reproduction.
Good Post
Good article.
Thanks…..above notes helped me lot….in a short time!!!