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What does homolog ortholog and paralog mean?

What does homolog ortholog and paralog mean?

Orthologous are homologous genes where a gene diverges after a speciation event, but the gene and its main function are conserved. If a gene is duplicated in a species, the resulting duplicated genes are paralogs of each other, even though over time they might become different in sequence composition and function.

What are Orthologues and Paralogues?

Orthologues: sequences have common ancestor and have split due to speciation event. • Paralogues: sequences are the descendents of an ancestral gene that underwent a duplication event.

What is the difference between orthologs and paralogs?

“By definition, orthologs are genes that are related by vertical descent from a common ancestor and encode proteins with the same function in different species. By contrast, paralogs are homologous genes that have evolved by duplication and code for protein with similar, but not identical functions.”

What are gene homologues?

A gene related to a second gene by descent from a common ancestral DNA sequence. The term, homolog, may apply to the relationship between genes separated by the event of speciation (see ortholog) or to the relationship betwen genes separated by the event of genetic duplication (see paralog).

How is an orthologue related to a homologous gene?

A homologous gene that is related to those in different organisms by descent from the DNA of a common ancestor and that may or may not have the same function. [Back-formation from orthologous : ortho- + (homo)logous .] American Heritage® Dictionary of the English Language, Fifth Edition.

Which is the best definition of an orthologue?

Homologues which diverged by a speciation event. There are four types of orthologues: many-to-many orthologues (ortholog_many2many) between-species paralogues – only as exceptions Genes in different species and related by a speciation event are defined as orthologues.

What is the meaning of the word homologue?

something that has a similar position, structure, value, or purpose to something else: Chronic fatigue syndrome has had its homologues for many years, including such poorly described disease states as neurasthenia.

Can a orthologue be found in the same species?

By definition, orthologs can never be found in the same species. The scenario on the right (2) shows what happens if the order of events is reversed: first, the ancestral lineage harboring the gene splits by speciation into two new species, both of which inherit the gene.