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#gene duplication

3 public questions tagged with this topic.

Gene and Genome

Processed pseudogenes are formed by:

Processed or retrotransposed pseudogenes originate via retrotransposition of mature mRNA intermediate. Line-1 encoded endonuclease and reverse transcriptase recognize polyadenylated transcript, generating cDNA copy integrated into genome at new location. Hallmarks include absence of introns, presence of 3' polyA tract remnant, flanking direct repeats and lack of promoter, reflecting derivation from spliced message rather than DNA duplication. They are typically transcriptionally silent due to missing regulatory elements, accumulate mutations and serve as molecular fossils of ancestral gene expression patterns, abundant in mammalian genomes.

Ref: Vanin EF, Annu Rev Genet 1985: Processed Pseudogenes Formed by Reverse Transcription of mRNA

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Gene and Genome

Paralogous genes arise due to:

Paralogy describes homology relationship between genes within same species that diverged after duplication event. Duplicate loci initially identical reside in different chromosomal positions; over time independent mutations lead to sequence divergence. Functional fate includes retention of similar function, diversification toward new substrate specificity or loss of function. This contrasts orthology, where genes separate via speciation, retaining similar function across species. Human alpha and beta globin genes, HOX clusters and olfactory receptors are classic paralog examples originating from ancient tandem duplications, expanding genome coding potential beyond original template.

Ref: Koonin EV, Annual Review Genetics 2005: Orthologs, Paralogs and Evolutionary Genomics, Gene Duplication

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Gene and Genome

Gene duplication followed by divergence can produce:

Gene family expansion occurs through duplication events including tandem duplication, segmental duplication and whole-genome duplication. Paralogous copies initially redundant undergo divergent selective pressures: subfunctionalization partitioning ancestral functions or neofunctionalization acquiring novel interactions. Some duplicates accumulate disabling mutations such as premature stops or frameshifts, becoming non-functional pseudogenes transcribed poorly or not translated. Globin clusters exemplify this process, containing functional embryonic, fetal and adult genes alongside pseudogenes. Thus duplication followed by divergence can produce both functional paralogs and pseudogenes, driving proteome complexity.

Ref: Ohno S., Evolution by Gene Duplication, 1970; Zhang J., Genetics 2003: Paralogs and Pseudogenes

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