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Bacteria Chapter 34 Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Prevalence of Bacteria • Bacteria are the oldest, structurally simplest, and the most abundant forms of life on earth. Abundant for over 2 billion years before the appearance of eukaryotes. 5,000 different kinds currently recognized. - Based primarily upon their metabolic and genetic characteristics. Can only be properly characterized on a defined medium. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Prevalence of Bacteria • Bacterial Form Bacillus (Bacilli) straight and rod-shaped. Coccus (Cocci) spherical shaped. Spirillus (Spirilla) long and helical shaped. Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Prevalence of Bacteria • Prokaryotes versus Eukaryotes Multicellularity Cell Size Chromosomes Cell Division and Recombination Internal Compartmentalization Flagella Metabolic Diversity Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Bacterial Surface • Bacterial Surface Cell wall maintains shape and protects the cell from swelling and rupturing. - Usually consist of peptidoglycan. Gram Positive - Thicker peptidoglycan Gram Negative - Thinner peptidoglycan Flagella - Slender protein - locomotion Pili - Hairlike structures - attachment Endospores - Resistant to environment. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Gram Stain Copyright © McGraw-Hill Companies Permission required for reproduction or display Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Cell Interior • • • Internal Membranes Invaginated plasma membrane. Nucleoid Region Lack nucleus - Genes encoded with single double-stranded DNA. Ribosomes Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Bacterial Diversity • Key Classification Characteristics Photosynthetic or Nonphotosynthetic Motile or Nonmotile Unicellular or Multicellular Spore Formation by Division or Transverse Binary Fission. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Bacterial Diversity • Comparing Archaebacteria and Eubacteria Cell Wall - Archaebacteria lack peptidoglycan. Plasma Membranes - Composed of different lipids. Gene Translation Machinery - Archaebacteria similar to eukaryotes. Gene Architecture - Eubacteria not interrupted by introns. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Bacterial Variation • Two Process create bacterial variation: Mutation - Spontaneous errors in DNA replication. Genetic Recombination - Occurs by gene transfer from one cell to another by viruses or conjugation. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Bacterial Metabolism • • Autotrophs Obtain carbon from inorganic CO2. - Photoautotrophs - Sunlight - Chemoautotrophs - Inorganic Chemicals Heterotrophs Obtain carbon from organic molecules. - Photoheterotrophs - Sunlight - Chemoheterotrophs - Organic Molecules Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Bacterial Metabolism • How Heterotrophs Infect Host Organisms Proteins secreted by Type III System. - May be used to transfer other virulence proteins into nearby eukaryotic cells. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Human Bacterial Diseases • • Tuberculosis Afflicts respiratory system and easily transmitted from person to person through the air. Dental Caries (cavities) Tooth decay caused by bacteria present in plaque. - High sugar diets increase tooth decay. Lactic acid bacteria ferment sugars and reduce pH, thus degenerating tooth enamel. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Human Bacterial Diseases • Sexually Transmitted Diseases Gonorrhea (Neisseria gonorrhoeae) Syphilis (Treponema pallidum) Chlamydia (Chlamydia trachomatis) Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Importance of Bacteria • • • • • • Largely responsible for creating atmospheric properties. Contribute to carbon balance. Nitrogen Fixation Industrial Processes Fermentation of lactose into lactic acid. - Milk, Cheese, Yogurt Genetic Engineering Removal of environmental pollutants. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies