lecture 11 - Gene Transfer, Mutation and Genome Evolution...

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Unformatted text preview: Gene Transfer, Mutation and Genome Evolution The Mosaic Nature of Genomes Microbial genomes have undergone extensive gene loss and gain DNA sequence is not static Mutations of single bases slow, but accumulated through time Large deletions Large insertions of sequence genetic islands Transferred from other species horizontal gene transfer Introduce new functions Maintained if confer growth advantage in specific environmental conditions natural selection Plasmids Horizontal Gene Transfer Horizontal or lateral gene transfer : genes transferred from one organism to another ( donor to recipient ) As opposed to vertical gene transfer: from mother cell to daughter cells through cell division Three transfer processes: Transformation : Natural transformation: free (naked) DNA taken up from the environment and then integrated into genome Plasmid transformation Conjugation : cell-cell contact (sex pilus) Transduction : DNA transfer is mediated by bacteriophage Discovery of Transformation First demonstrated with Streptococcus pneumoniae by Griffith (1928); Avery and McLeod (1943): mortality experiment with mice using smooth (with capsule, virulent) and rough (no capsule, nonvirulent) strain Tested polysaccharide, protein, RNA, and DNA, and only DNA from smooth strain conferred virulence to rough strain Gene Transfer: Transformation...
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This note was uploaded on 01/31/2011 for the course BIO 121 taught by Professor Ma during the Winter '10 term at UC Riverside.

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lecture 11 - Gene Transfer, Mutation and Genome Evolution...

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