Paralog

Paralog is a term used in genetics to refer to one of two or more genes that are derived from the same ancestral gene and are located within the same organism. Paralogs typically have similar sequences and are often functionally related, although they may have diverged to some extent during the course of evolution.

Origin and Evolution

Paralogs originate through gene duplication, a process in which a gene is copied and the copy is retained in the genome. This can occur through a variety of mechanisms, including unequal crossing over, replication errors, and transposition events. Once a gene has been duplicated, the two copies can evolve independently. This can lead to the development of new functions, a process known as neofunctionalization, or to the partitioning of the original function between the two copies, known as subfunctionalization.

Function and Significance

Paralogs can play important roles in genetic diversity and adaptation. Because they are derived from the same ancestral gene, paralogs often have similar functions. However, the independent evolution of paralogs can lead to the development of new functions, which can contribute to the adaptation of an organism to its environment. Paralogs can also compensate for the loss of function of other genes, providing a form of genetic redundancy that can enhance the survival of an organism.

Identification and Classification

Paralogs can be identified through sequence alignment, a process that involves comparing the sequences of genes to identify regions of similarity. This can be done using a variety of computational tools, such as BLAST and ClustalW. Once paralogs have been identified, they can be classified based on their sequence similarity and functional characteristics. This can provide insights into the evolutionary history of the genes and the organisms in which they are found.

See Also

• Ortholog
• Homologous genes
• Gene duplication
• Molecular evolution