Introns and Exons

- - March 31 1997 AP. Biology essay Introns and Exons.         The finding of the Introns and the exons was one of the most significant discoveries in genetics in the past fifteen years. split genes were discovered when lack of relation between DNA sequences were seen during. DNA- mRNA hybridation. For all new mRNA, they must be transcribed by RNA polymerase enzymes. The transcription begins at the promoter sequence on the DNA and works down, thus the nucleotide …

…near to the branch point. Then the introns it self catalyze the making of the loop joining the two exons. The difference between self splicing intron and one which require the spliceosome is that the non-self splicing introns can split any introns, almost any size. This helps the organism to survive mutations. When a mutation forms, some times the self splicing introns lose it¹s hairpin structure not allowing it self to be spliced off.