BIO 121 Lecture Notes - Lecture 6: Guanosine, Endonuclease, Polyadenylation
23 Nov 2020
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Document Summary
Rna poly i transcribes the majority of rrna genes. Rna poly ii transcribes mrna and genes that code for non-coding rnas such as those found in spliceosomes. Rna poly iii transcribes small stable rna such as trna or 5s rrna (used in ribosome) mrna. Joined to initial 5" nucleotide through triphosphate linkage. Added near the end of the 1 sequence (aataa sequence recognized by endonuclease cuts nucleic acids (20 bp downstream of recognition) and adds polyatail. Non coding rna sequences known as introns are recognized and removed. Contain sequences that code for the protein (destined for export to cytoplasm. Splicing is done by snrnps complementary to recognition sequences in the rna transcript. When snrnps come together called spliceosome. Left boundary of intron is cut then nucleotides near the right (3" end) forms lariat loop. Advantage: ability to produce multiple different variations of a protein using the same gene.
