BIOC 2580 Study Guide - Final Guide: Surface 3, Cas9, Methyltransferase
16 Dec 2015
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Document Summary
Methylase recognizes the same sequence as the restriction enzyme. Methylates the sequence so the enzyme will only cut foreign mrna. Similar to rnai in eukaryotes, uses small ssrnas to target foreign dna. Locus is embedded in bacterial genome which is transcribed, processed and loaded into a nuclease protein (cas) Crispr guides the protein to foreign dna target and protein cleaves all. Four cas genes precede the guide rna and form a cas complex. Before crispr sequence is a unique leader sequence followed by a bunch of crispr repeats which can all be identical or can be different. Each repeat is separated by a spacer, with each spacer representing a guide rna. Guide rna is 100% identical to the foreign sequence it directs cas to cleave. Different from eukaryotic rnai because the bacteria somehow have a memory of being invaded by specific viruses or foreign dna and have retained the genetic information.
