Paralogous genes (or paralogs) are a particular class of homologous genes. They are the result of gene duplication and the gene copies resulting from the duplication are called paralogous of each other.
What is a Paralog?
Definition. One of a set of homologous genes that have diverged from each other as a consequence of genetic duplication. For example, the mouse alpha globin and beta globin genes are paralogs. The relationship between mouse alpha globin and chick beta globin is also considered paralogous.
What is meant by gene family?
Gene family: A group of genes that are related in structure and often in function. The genes in a gene family are descended from an ancestral gene. For example, the hemoglobin genes belong to one gene family that was created by gene duplication and divergence.
What do paralogs do?
Paralogs typically have the same or similar function, but sometimes do not. Due to lack of the original selective pressure upon one copy of the duplicated gene, this copy is free to mutate and acquire new functions. Paralogous sequences provide useful insight into the way genomes evolve.
How do paralogs form?
Homologous sequences are paralogous if they were separated by a gene duplication event: if a gene in an organism is duplicated to occupy two different positions in the same genome, then the two copies are paralogous. Paralogous genes often belong to the same species, but this is not necessary.
How are paralogs formed?
Paralogous genes are genes present in a particular organism that are related to each other through a gene duplication event. A particular paralog in one organism can be orthologous to a gene in another organism, or it could have arisen independently in an ancestor, through a gene duplication event.
How do paralogs evolve?
Orthologs and paralogs are two fundamentally different types of homologous genes that evolved, respectively, by vertical descent from a single ancestral gene and by duplication.
What is an orthologs?
Orthologs are defined as genes in different species that have evolved through speciation events only. Paralogs, on the other hand arise by duplication events [2].
What is an example of a gene family?
How do paralogs arise?
Unlike orthologous genes, a paralogous gene is a new gene that holds a new function. These genes arise during gene duplication where one copy of the gene receives a mutation that gives rise to a new gene with a new function, though the function is often related to the role of the ancestral gene.
What is an example of a paralog of a gene?
For example, the hemoglobin gene of humans and the myoglobin gene of chimpanzees are paralogs. Paralogs can be split into in-paralogs (paralogous pairs that arose after a speciation event) and out-paralogs (paralogous pairs that arose before a speciation event).
Do all paralogs have the same function?
Paralogs typically have the same or similar function, but sometimes do not. Due to lack of the original selective pressure upon one copy of the duplicated gene, this copy is free to mutate and acquire new functions. Paralogous sequences provide useful insight into the way genomes evolve.
What are between species out-paralogs and within species paralogs?
Between species out-paralogs are pairs of paralogs that exist between two organisms due to duplication before speciation. Within species out-paralogs are pairs of paralogs that exist in the same organism, but whose duplication event happened after speciation. Paralogs typically have the same or similar function, but sometimes do not.
What is the function of a RecA/Rad51 paralog?
RAD51 paralogs are products of gene duplication events of RecA/RAD51 genes that function as accessory proteins in HR repair ( Table I; Ref. 220 ).
