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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 27 Bacteria and Archaea Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: Masters of Adaptation • Utah’s Great Salt Lake can reach a salt concentration of 32% • Its pink color comes from living prokaryotes © 2011 Pearson Education, Inc. • Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms – microscopic – more in a handful of fertile soil than the number of people who have ever lived • Prokaryotes are divided into two domains: bacteria and archaea Video: Tubeworms © 2011 Pearson Education, Inc. Concept 27.1: Structural and functional adaptations contribute to prokaryotic success • Earth’s first organisms • unicellular • prokaryotic cells: 0.5–5 µm – Eukaryotic Cells: 10–100 µm • Shape: spheres (cocci), rods (bacilli), and spirals © 2011 Pearson Education, Inc. Cell-Surface Structures • Cell Wall: maintains cell shape, cell protection, and prevents it from bursting in a hypotonic environment – contain peptidoglycan: a network of sugar polymers cross-linked by polypeptides • Archaea: lack peptidoglycan • Gram stain: classify bacteria – Gram-positive: simpler walls with a large amount of peptidoglycan – Gram-negative: less peptidoglycan and an outer membrane that can be toxic © 2011 Pearson Education, Inc. Figure 27.3 (a) Gram-positive bacteria: peptidoglycan traps crystal violet. Gram-positive bacteria (b) Gram-negative bacteria: crystal violet is easily rinsed away, revealing red dye. Gram-negative bacteria Carbohydrate portion of lipopolysaccharide Cell wall Peptidoglycan layer Cell wall Plasma membrane 10 m Outer membrane Peptidoglycan layer Plasma membrane • Many antibiotics target peptidoglycan and damage bacterial cell walls • Gram-negative bacteria: > antibiotic resistant • capsule: protein layer that covers many prokaryotes • Fimbriae: stick to their substrate or other individuals in a colony • Pili (or sex pili) are longer than fimbriae and allow prokaryotes to exchange DNA © 2011 Pearson Education, Inc. Figure 27.5 Fimbriae 1 m Motility • Taxis: ability to move toward or away from a stimulus • Chemotaxis is the movement toward or away from a chemical stimulus – Flagella: scattered about the surface or concentrated at one or both ends Video: Prokaryotic Flagella (Salmonella typhimurium) © 2011 Pearson Education, Inc. Figure 27.6 Flagellum Filament Hook Motor Cell wall Plasma membrane Rod Peptidoglycan layer 20 nm Internal Organization and DNA • lack complex compartmentalization • Some have specialized membranes that perform metabolic functions – infoldings of the plasma membrane • • • • less DNA than the eukaryotes circular chromosome located in the nucleoid region Plasmid: smaller rings of DNA © 2011 Pearson Education, Inc. Figure 27.7 1 m 0.2 m Respiratory membrane Thylakoid membranes (a) Aerobic prokaryote (b) Photosynthetic prokaryote Figure 27.8 Chromosome Plasmids 1 m Reproduction and Adaptation • prokaryotic reproduction: – They are small – They reproduce by binary fission – They have short generation times • Endospore: metabolically inactive, which can remain viable in harsh conditions for centuries • Their short generation time allows prokaryotes to evolve quickly © 2011 Pearson Education, Inc. Figure 27.9 Endospore Coat 0.3 m Figure 27.10 EXPERIMENT Daily serial transfer 0.1 mL (population sample) Old tube (discarded after transfer) New tube (9.9 mL growth medium) Population growth rate (relative to ancestral population) RESULTS 1.8 1.6 1.4 1.2 1.0 0 5,000 10,000 15,000 Generation 20,000 Concept 27.2: Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes • Three factors contribute to this genetic diversity: – Rapid reproduction – Mutation – Genetic recombination © 2011 Pearson Education, Inc. Transformation, Transduction, & Conjugation • Transformation: prokaryotic cell takes up and incorporate foreign DNA from the surrounding environment • Transduction: movement of genes between bacteria by bacteriophages (viruses that infect bacteria) • Conjugation: genetic material is transferred between prokaryotic cells – A donor cell attaches to a recipient by a pilus, pulls it closer, and transfers DNA © 2011 Pearson Education, Inc. Figure 27.11-4 Phage A B Donor cell A B A Recombination A A B A B Recipient cell Recombinant cell Figure 27.12 1 m Sex pilus Concept 27.3: Diverse nutritional and metabolic adaptations have evolved in prokaryotes • Prokaryotes can be categorized by how they obtain energy and carbon – – – – Phototrophs obtain energy from light Chemotrophs obtain energy from chemicals Autotrophs require CO2 as a carbon source Heterotrophs require an organic nutrient to make organic compounds © 2011 Pearson Education, Inc. Metabolism • Prokaryotic metabolism varies with respect to O2 – Obligate aerobes require O2 for cellular respiration – Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration – Facultative anaerobes can survive with or without O2 – In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3) © 2011 Pearson Education, Inc. Archaea • Archaea share certain traits with bacteria and other traits with eukaryotes – extremophiles: archaea that live in extreme environments • • halophiles highly saline Thermophiles: very hot environments – Methanogens: live in swamps and marshes and produce methane as a waste product • poisoned by O2 © 2011 Pearson Education, Inc. Figure 27.16 Proteobacteria: gram • Alpha Proteobacteria – Rhizobium: forms root nodules in legumes and fixes atmospheric N2 – Agrobacterium: produces tumors in plants and is used in genetic engineering • Beta Proteobacteria: soil bacterium converts NH4+ to NO2– • Gamma Proteobacteria – Pathogens: Legionella, Salmonella, and Vibrio cholerae – Escherichia coli • Epsilon Proteobacteria: Campylobacter (blood poisoning) and Helicobacter pylori (stomach ulcers) © 2011 Pearson Education, Inc. • Chlamydias: blindness and nongonococcal urethritis by sexual transmission • Spirochetes:Treponema pallidum (syphilis) and Borrelia burgdorferi (Lyme disease) • Cyanobacteria: generate O2 – Plant chloroplasts © 2011 Pearson Education, Inc. Gram-Positive Bacteria • Gram-positive bacteria include – – – – Actinomycetes, which decompose soil Bacillus anthracis, the cause of anthrax Clostridium botulinum, the cause of botulism Some Staphylococcus and Streptococcus, which can be pathogenic – Mycoplasms, the smallest known cells © 2011 Pearson Education, Inc. Chemical Recycling • Chemoheterotrophic prokaryotes: decomposers, breaking down dead organisms and waste products • Prokaryotes: increase the availability of nitrogen, phosphorus, and potassium for plant growth • Prokaryotes can also “immobilize” or decrease the availability of nutrients © 2011 Pearson Education, Inc. Ecological Interactions • Symbiosis: two species live in close contact: a larger host and smaller symbiont – Mutualism: both benefit – Commensalism: one benefits while neither harming nor helping the other – parasitism, an organism called a parasite harms but does not kill its host • pathogens © 2011 Pearson Education, Inc. Mutualistic & Pathogenic Bacteria • Human intestines are home to about 500–1,000 species of bacteria • Many of these are mutalists and break down food that is undigested by our intestines • Prokaryotes cause about half of all human diseases – For example, Lyme disease is caused by a bacterium and carried by ticks © 2011 Pearson Education, Inc. Figure 27.20 5 m Prokaryotes in Research and Technology • DNA technology – E. coli is used in gene cloning – Agrobacterium tumefaciens: produce transgenic plants • make natural plastics • Bioremediation: organisms to remove pollutants from the environment • Produce vitamins, antibiotics, and hormones • Produce ethanol from waste biomass © 2011 Pearson Education, Inc. Figure 27.21 (a) (c) (b) LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 28 Protists Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Concept 28.1: Most eukaryotes are single-celled organisms • Protists constitute a polyphyletic group, and Protista is no longer valid as a kingdom • Protists are eukaryotes – organelles and are more complex than prokaryotic cells – Most are unicellular, but there are some colonial and multicellular species © 2011 Pearson Education, Inc. • Protists, the most nutritionally diverse of all eukaryotes, include – Photoautotrophs, which contain chloroplasts – Heterotrophs, which absorb organic molecules or ingest larger food particles – Mixotrophs, which combine photosynthesis and heterotrophic nutrition • Reproduce: asexually, sexually, or by meiosis and fertilization © 2011 Pearson Education, Inc. Endosymbiosis in Eukaryotic Evolution • protist diversity endosymbiosis • Endosymbiosis: a unicellular organism engulfs another cell and becomes an organelle in host cell – Mitochondria (aerobic prokaryote) & Plastids (photosynthetic cyanobacterium) © 2011 Pearson Education, Inc. Figure 28.2c Secondary endosymbiosis Plastid Euglenids Secondary endosymbiosis Green alga Chlorarachniophytes Types of Protist • Dinoflagellates: two flagella – both marine and freshwater phytoplankton – Toxic “red tides” are caused by dinoflagellate blooms • Apicomplexans: parasites of animals – Plasmodium: malaria – Approximately 900,000 people die each year from malaria • Brown algae: kelp or sea-weed • Oomycetes include water molds, white rusts, and downy mildews – potato blight caused by Phytophthora infestans © 2011 Pearson Education, Inc. Figure 28.10-3 Inside mosquito Inside human Merozoite Sporozoites (n) Liver Liver cell Apex Oocyst MEIOSIS Red blood cell Merozoite (n) Zygote (2n) 0.5 m Red blood cells FERTILIZATION Gametes Gametocytes (n) Key Haploid (n) Diploid (2n) Diatoms • Diatoms are unicellular algae with a unique twopart, glass-like wall of hydrated silica • Diatoms usually reproduce asexually, and occasionally sexually © 2011 Pearson Education, Inc. Figure 28.3c 50 m Diatom diversity Concept 28.5: Red algae and green algae are the closest relatives of land plants Concept 28.6: Unikonts include protists that are closely related to fungi and animals Concept 28.7: Protists play key roles in ecological communities © 2011 Pearson Education, Inc. Symbiotic Protists • Some protist symbionts benefit their hosts – Dinoflagellates nourish coral polyps that build reefs – Wood-digesting protists digest cellulose in the gut of termites © 2011 Pearson Education, Inc.