Bacteria enetics Exchange of Genetic Information DiQu(瞿涤) MOH&MOE Key Lab of Medical Molecular Virology Shanghai Medical College, Fudan University 复旦大学基础医学院 医学分子病毒学教育部卫生部重卢实验室 Chapter 7
Bacteria Genetics & Exchange of Genetic Information Shibo Jiang (姜世勃) MOH&MOE Key Lab of Medical Molecular Virology Shanghai Medical College, Fudan University 复旦大学上海医学院分子病毒学教育部/卫生部重点实验室 Di Qu (瞿涤) MOH&MOE Key Lab of Medical Molecular Virology Shanghai Medical College, Fudan University 复旦大学基础医学院 医学分子病毒学教育部/卫生部重点实验室 Chapter 7
Key words Chromsome Plasmid Transposable genetic Elements Phage Lysophage(temperate), virulent phage prophage, lysogen /lysogeny Horizontal gene transfer Transformation transduction General transduction Lysogenic( specific) transduction/conversion Conjugation(transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells) F factor, Hfr, R plasmid
Key Words Chromsome Plasmid Transposable Genetic Elements Phage -Lysophage (temperate), virulent phage prophage, lysogen /lysogeny Horizontal Gene transfer Transformation Transduction General transduction Lysogenic （specific）transduction/conversion Conjugation (transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells) F factor，Hfr， R plasmid
Copyright o The McGraw-Hill Companies, Inc. Permission required for reproduction or display O-O DNA DNA Duplicate of original molecule Transcription All organisms have dna and rna as genetic material RNA All organisms use the same Translation nucleotides All organisms replicate, transcribe and translate dna Protein The central dogma of molecular biology
The central dogma of molecular biology All organisms have DNA and RNA as genetic material All organisms use the same nucleotides All organisms replicate, transcribe and translate DNA
Growth of bacteria Bacterial Multiplication- Binary Division Cell wall Cell membrane Elongated nucleoid Nucleoid divides: Chromosome(ds dNA) cell wall and membrane begin to form number doubled transverse septum Plasmid( ds DNA) Transverse septum number becomes complete Daughter cells separate
Growth of bacteria Bacterial Multiplication - Binary Division Chromosome (ds DNA) number doubled Plasmid (ds DNA) number ?
General characteristics of bacterial genetics Bacterial dna can be altered by mutations Mutations can result in changes in proteins New traits diversity acquisition of (antibiotics)resistance New traits can be transmitted to daughter cells other microbes Horizontal Gene transfer)
General characteristics of bacterial genetics Bacterial DNA can be altered by mutations Mutations can result in changes in proteins - New traits -diversity -acquisition of (antibiotics) resistance New traits can be transmitted to -daughter cells -other microbes （Horizontal Gene transfer）
Chapter 7 Bacterial Genetic material Chromsome: the prokaryotic genome is circular, haploid Genome size very in species: Table 7-1 Plasmid: mobile Transposable Genetic Elements: mobile elements, integrate into chromsome or plasmid Bacterial DNA Plasmids carried genes,. drug resistant -insertion mutation Bacteriaphage(phage) RNA-mRNA rRNA In prokaryotes, an mRNA molecule carry information for several genes(eukaryotes an mRNA for one gene) The ribosomes are 70s in prokaryotes vs 80S in eukaryotes Transcription: synthesis of rna from a dna template Translation: formation of a protein
Bacterial Genetic material Chromsome: the prokaryotic genome is circular, haploid Genome size very in species: Table 7-1 Plasmid： mobile Transposable Genetic Elements：mobile elements, integrate into chromsome or plasmid, -carried genes, …drug resistant -insertion mutation Bacteriaphage (phage) RNA-mRNA, rRNA -In prokaryotes, an mRNA molecule carry information for several genes (eukaryotes an mRNA for one gene) -The ribosomes are 70S in prokaryotes vs 80S in eukaryotes -Transcription: synthesis of RNA from a DNA template -Translation: formation of a protein Chapter 7
Mutations in bacteria Diploid allele mutation -recessiveness Haploid mutation -dominance Rare mutations are expressed in bacteria Bacteria are haploid Rapid growth rate (bacteria generation time/doubling time? Ecoli >1010m Selective advantage enriches for mutants antibiotics, nutrients Horizontal gene transfer
Mutations in Bacteria • Mutations arise in bacterial populations – Point mutation (synonymous/nonsynonymous substitution) Induced or spontaneous mutations – Genetic Recombination Why there are so many bacterial mutants? Rare mutations are expressed in bacteria - Bacteria are haploid - Rapid growth rate (bacteria generation time/doubling time? E.coli) - >1010/ml - Selective advantage enriches for mutants antibiotics, nutrients… Horizontal gene transfer Diploid allele mutation –recessiveness Haploid mutation –dorminance
Plasmids Plasmids are circular double strand dna molecules Definition: Extrachromosomal genetic elements Replicate independently of the bacterial chromosome (replicon) encode a variety of genes usually not essential bacterial genes but may give bacterium new properties (antibiotic resistance, virulent, etc. ) can lost during culture Size vary widely, mobile and can be transferred between individuals and among species (host range Plasmids are used in genetic engineering as gene transfer vectors Episome(virology)-a plasmid that can integrate into the chromosome
Plasmids • Plasmids are circular double strand DNA molecules • Definition: • Extrachromosomal genetic elements • Replicate independently of the bacterial chromosome (replicon) encode a variety of genes usually not essential bacterial genes but may give bacterium new properties (antibiotic resistance, virulent, etc.), can lost during culture. • Size vary widely, mobile and can be transferred between individuals and among species (host range) • Plasmids are used in genetic engineering as gene transfer vectors • Episome (virology) - a plasmid that can integrate into the chromosome 8
Table 7-2 Examples of Metabolic Activities Determined by Plasmids Organism Activity Pseudomonas species Degradation of camphor, toluene, octane, salicylic acid Bacillus a-Amylase stearothermophilus Alcaligenes eutrophus Utilization of H2 as oxidizable energy source Escherichia coli Sucrose uptake and metabolism, citrate uptake Klebsiella species Nitrogen fixation Streptococcus(group N) Lactose utilization, galactose phosphotransferase system, citrate metabolism Rhodospirillum rubrum Synthesis of photosynthetic pigment Flavobacterium species Nylon degradation
Table 7–2 Examples of Metabolic Activities Determined by Plasmids Organism Activity Pseudomonas species Degradation of camphor, toluene, octane, salicylic acid Bacillus stearothermophilus α-Amylase Alcaligenes eutrophus Utilization of H2 as oxidizable energy source Escherichia coli Sucrose uptake and metabolism, citrate uptake Klebsiella species Nitrogen fixation Streptococcus (group N) Lactose utilization, galactose phosphotransferase system, citrate metabolism Rhodospirillum rubrum Synthesis of photosynthetic pigment Flavobacterium species Nylon degradation
Copyright o The McGraw-Hill Companies, Inc, Permission required for reproduction or display. Some Plasmid-Coded Traits Trait Organisms in Which Trait s found Antibiotic resistance Eschenchia coli, Salmonella sp Neisseria sp, Staphylococcus sp Shigella sp, and many other organisms Pilus synthesis E. coli, Pseudomonas sp Tumor formation in plants Agrobacterium tumefaciens Nitrogen fixation (in plants) Rhizobium sp Oil degradation Pseudomonas sp Gas vacuole production Halobacterium sp nsect toxin synthesis Bacillus thuringiensis Plant hormone synthesis Pseudomonas sp Antibiotic synthesis Streptomyces sp. Increased virulence Yersinia enterocolitica Toxin production Bacillus anthracis
