BIOC 4403 Lecture Notes - Lecture 8: Entamoeba, Bacteria, Endonuclease
23 Mar 2017
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Document Summary
Most superfamilies have ancient origins earlier prokaryotic types of transposable elements. It can be inferred that superfamilies existed at the origin of current diversity. Their main feature is the presence of a gene encoding a dna polymerase b. Polintons carry their own dna-dependent dna polymerase. Polintons originated from virophages (viruses that infect viruses) Usually large and have few conserved structural features, which makes them difficult to find and identify. Helitrons frequently capture host genes, shuffle exons and induce structural changes in the host chromosomes, generating great structural variability especially in several plant species. First discovered during studies of repetitive dna segments in plants but found in all eukaryotic genomes. Helitron encoded proteins are composed of a rolling-circle (rc) replication initator (rep) and a dna helicase domain (hel) Rep involved in catalytic reactions for endonuclelytic cleavage, dna transfer and ligation: contains a motif for dna binding and one that catalyzes dna cleavage and ligation.
