05.+Bacterial+Genetics

05.+Bacterial+Genetics - Bacterial Genetics Bacterial...

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Bacterial Genetics Page 1 Bacterial Genetics Bacterial Genome Gene Pools (G= gene set) • Core Gene Pool (80-99% of Bacterial Genes) - Genes that are Part of a Bacterium ʼ s Chromosome - Homogeneous G + C Content Similar G + C Content implies similar DNA and similar Taxonomic Relatedness. She doth teach the Torches to burn bright It seems she hangs upon the Cheek of Night Like a rich Jewel in a Ethiope ʼ s Ear. - Encode for essential Proteins involved in Structure and Function An E. coli ʼ s Core Gene Pool is what makes a particular Bacterium look and function like an E. coli . The Core Gene Pool is like the Parts used to make a “stock” Honda Civic. • Flexible Gene Pool (01-20% of Bacterial Genes) - Blocks of Genes (“Genomic Islands”) that are Bacteriophage-derived, Plasmid-derived, or Transposon-derived • 10-100 Kbp Clusters of Genes with related Functions - Pathogenicity Islands (PAI) These were the first Genomic Islands to be discovered (in pathogenic E. coli in 1994). They carry Genes for Virulence. There are also Ecological and Symbiosis Islands. - Very different G + C Content from Core Gene Pool Very different G + C Content would imply very different DNA and very distant Taxonomic Relatedness. She doth teach the Torches to burn bright It seems she hangs upon the Cheek of Night Like Bad-Ass Bling in a Ethiope ʼ s Ear. - Encode for non-essential Proteins that may confer the Bacterium with specific Advantages under different Circumstances An E. coli ʼ s Flexible Gene Pool is what makes a particular E. coli a beneficial Gut E. coli , a harmless Lab Strain or a nasty Pathogen. The Flexible Gene Pool is like the Parts used to “slam” a Honda Civic.
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Bacterial Genetics Page 2 Core Gene Pool Most Bacteria have a single Circular Chromosome There are Exceptions: Rhodobacter sp. (a Purple Bacterium) has two circular Chromosomes. Streptomyces sp. (an Actinomycete) has a Linear Chromosome. Rapidly growing Bacteria frequently contain more than one Copy of their Chromosome. Bacterial Chromosome Size ranges from ~580 Kbp to ~10 Mbp • Genome Size is Species-Specific There are a lot of different E. coli Strains and they range from harmless, attenuated Lab Strains (E. coli K12) to wildly pathogenic Strains (E. coli 0157:H7) but they all have Genomes of ~4.6 Mbp. The E. coli Genome is composed of 4,639,221 Basepairs • 88% of the E. coli Genome consists of ~4000 Structural Genes • 10% of the Genome consists of Regulatory Sequences - Origin of Replication (oriC, 84 Minutes) The Origin of Replication is a Sequence at which Bi-Directional Chromosome Replication originates. The oriC is located at 84 Minutes (Stay Tuned). - Terminus of DNA Replication (terC, 31 Minutes) The Terminus of Replication is a Sequence at which Chromosome Replication terminates. The terC is located at 31 Minutes. - Promoters
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This note was uploaded on 08/23/2011 for the course MIC 101 taught by Professor Mann during the Spring '09 term at UC Davis.

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05.+Bacterial+Genetics - Bacterial Genetics Bacterial...

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