these transposons are first transcribed into RNA

these transposons are first transcribed into RNA - In the...

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----- these transposons are first transcribed into RNA. But in order to integrate into another site of the genome, the RNA must first be transcribed back into DNA. This occurs via the enzyme reverse transcriptase which is encoded by many transposons. Reverse transcriptase is a kind of DNA polymerase that can use RNA as a template . (Notice that we have here an exception to the dogma that information will only flow from DNA to RNA to protein. The information (the base sequence) in this case flows from RNA back to DNA.) Obviously, the movement of a transposon creates mutations in the target site
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Unformatted text preview: . In the overwhelming majority of cases: mutations will be a disadvantage to the cell. Example: transposon integrates directly into gene that codes for important protein ----- protein not functional anymore ----- cell may die. But mutations by transposons are probably important for evolution. Humans: among others one transposon 6 - 7 kb long called LINE (l ong in terspersede lement). Because of many former transpositions ----- occurs in about 50,000 copies in the genome -----...
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