Biology 3597A/B Lecture Notes - Lecture 12: Small Nuclear Rna, Reverse Transcriptase, Retrovirus
Document Summary
One of the ways we think we know repetitive elements are silent is through epigenetics. Retrotransposons reverse transcriptase go through dna-rna-dna cycle (like retroviruses) use reverse transposition to move around. Divide retrotransposons with ones with long terminal repeats (ltr) Retrotransposons similar to retroviruses contain remnants of genes we associate with retrovirus life cycle but now contain mutations so not harmful. Line autonomous contains all genes necessary for its own transposition. Line or sine cause either long or short depending on repetitive sequences. Lines autonomous retroviral in origin, more mutated then those ltrs. Sines do(cid:374)"t e(cid:374)(cid:272)ode rt or have open reading frames no proteins produced at all movement requires rt from line. Lines transcribed like a normal gene, then open reading frames in mrna form translated, then proteins used to reverse transcribe back to dna. Sines transcribed primarily by rp3 transcribes ribosomal rna, trna, small nuclear. Rna splicing- -- we think sines originated as trna not retroviral in origin.