A transposon is a segment of DNA that inserts itself into another section within the genome (i.e. ‘jumping' genes)

  • Transposition often results in the duplication of the transposable element
  • If the duplicated sequence then undergoes random mutation, a pseudogene will result

A pseudogene is a non-functional sequence of DNA that is homologous to an active gene

  • Pseudogenes may be processed (retrotransposed) or non-processed (duplicated)

Processed pseudogenes

  • Arise when a portion of an mRNA transcript is reverse transcribed back into DNA and inserted into the chromosomal DNA
  • Processed pseudogenes consequently lack introns and promoter sequences, but may include a poly-A tract
  • These pseudogenes may be randomly integrated anywhere in the genome

Non-processed pseudogenes

  • Arise as a result of gene duplication and subsequent inactivation by mutation
  • Non-processed pseudogenes will often be flanked by transcriptional regulatory elements (e.g. promoters, etc.)
  • These pseudogenes are usually located adjacent to the original gene

Pseudogene Formation