MCB 3020C Lecture Notes - Lecture 15: Horizontal Gene Transfer, Polyploid, Gene Duplication
Document Summary
Homologous genes: related sequences that imply common genetic ancestry. Entire genome duplications: saccharomyes cerevisiae duplicated its entire genome, then deleted most of it, example: arabidopsis, example: some bacterial genomes, parasitic bacteria frequently delete unnecessary genes, driving small genomes of endosymbionts. Horizontal gene transfer or lateral gene transfer: the transfer of genetic information between cells, as opposed to vertical inheritance from parental organism(s). In prokaryotes, at least three mechanisms: transformation, transduction, and conjugation. Detecting horizontal gene flow, how can you tell whether a gene comes from horizontal. The pan / core concept: genomes of bacterial species consist of two components: core genome: shared by all strains of the species, pan genome: includes core plus genes present in some but not all strains of the species. Pathogenicity islands (chromosomal islands) and the evolution of virulence: virulence factors: special proteins, toxins, enzymes that facilitate disease symptoms, pathogenicity islands: chromosomal regions clustering genes for virulence, examples: uropathogenic e. coli and staphylococcus aureus.
