Mol bio lecture notes 22 Feb 2010 DNA transposons use a cut and paste mechanism • Remember that DNA transposons contain a gene that codes for the transposase enzyme. This enzyme will bind to the inverted terminal repeats and aid in the excision and integration of the transposon into new locations within the genome • Also remember that DNA transposons are directly integrated into the genome without going through an mRNA intermediate • When DNA transposons excise they can sometimes take flanking genomic DNA with them (imprecise excision) Retrotransposons and retroviruses • Retrotransoposons and retroviruses code for an interase (transposase) and a polymerase called reverse transcriptase. • Both use an RNA intermediate (which is then copied into a double stranded DNA molecule (cDNA) before integration into the host genome). Why is this advantageous for a retrovirus? • A retrovirus like HIV also codes for virus coat proteins. polyA retrotransposons
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