Paralog

A **paralog** is a gene that has arisen from a duplication event within a single genome. Unlike orthologs, which are genes in different species that evolved from a common ancestor, paralogs are related genes within the same organism. They often have similar sequences and structures, reflecting their shared ancestry. However, after duplication, paralogs may diverge and acquire different functions, specializing for different roles within the cell or organism. This divergence can involve changes in gene regulation, protein structure, or the nature of the protein's interaction with other molecules. The study of paralogs helps to understand the evolutionary history of gene families and the diversification of biological functions.

Paralog meaning with examples

• The human genome contains numerous paralogs of the globin gene, including alpha-globin and beta-globin, responsible for oxygen transport. These paralogs originated from ancient gene duplication events, leading to specialized forms for different developmental stages and tissues. Their relatedness highlights the evolutionary plasticity of gene families.
• Researchers investigated the paralogs of a transcription factor gene in yeast. They discovered that while one paralog regulated cell cycle progression, the other played a role in stress response. The functional divergence demonstrated how paralogs could diversify to provide a wider range of cellular adaptations.
• Studying the paralogs of the Toll-like receptors in mice allows the researchers to pinpoint which of the paralogs are specific to different pathogens. Understanding which genes respond to what invaders helps in understanding immune response and possibly disease control and response.
• The evolution of metabolic pathways often involves the generation of paralogs. For instance, enzymes involved in the biosynthesis of a specific compound might arise through gene duplication, followed by functional divergence, resulting in increased efficiency or the capacity to produce a broader range of compounds.