BIOL 102 Lecture Notes - Lecture 12: Noncoding Dna, Snrnp, Start Codon
25 Jun 2016
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As they replicate their dna, the chromosomes get shorter until a cell cycle checkpoint prevents further division o cancer cells often express telomerase: dna transposons o pieces of dna that excise and then reinsert into the genome o composed of a segment of dna called the transposase gene, which has inverted repeating sequences on either side of it o signals transposase to splice the segment from the strand, and inserts it elsewhere, often in the middle of a gene coding sequence, causing a change in the dna sequence o transposons can be copied by the host cell"s dna break repair. Template mediated repair occurs, which means that an enzyme adds base pairs complementary to the other strand into the empty gap, creating another transposon where the other one used to be: retrotransposons o move through an rna intermediate o require reverse transcriptase to do so o copy themselves to rna, then back to dna that may integrate with the genome.
