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Chapter 27 Presentation

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  • Figure 27.1 Why is this lakebed red?
  • Figure 27.2 The most common shapes of prokaryotes
  • Figure 27.3 Gram staining
  • Figure 27.3 Gram staining
  • Figure 27.3 Gram staining
  • Figure 27.3 Gram staining
  • Figure 27.4 Capsule
  • Figure 27.5 Fimbriae
  • Figure 27.6 Prokaryotic flagellum
  • Figure 27.6 Prokaryotic flagellum
  • Figure 27.6 Prokaryotic flagellum
  • Figure 27.7 Specialized membranes of prokaryotes
  • Figure 27.7 Specialized membranes of prokaryotes
  • Figure 27.7 Specialized membranes of prokaryotes
  • Figure 27.8 A prokaryotic chromosome and plasmids
  • Figure 27.9 An endospore
  • Figure 27.10 Can prokaryotes evolve rapidly in response to environmental change?
  • Figure 27.10 Can prokaryotes evolve rapidly in response to environmental change?
  • Figure 27.10 Can prokaryotes evolve rapidly in response to environmental change?
  • Figure 27.11 Transduction
  • Figure 27.11 Transduction
  • Figure 27.11 Transduction
  • Figure 27.11 Transduction
  • Figure 27.12 Bacterial conjugation
  • Figure 27.13 Conjugation and recombination in E. coli
  • Figure 27.13a Conjugation and recombination in E. coli
  • Figure 27.13a Conjugation and recombination in E. coli
  • Figure 27.13a Conjugation and recombination in E. coli
  • Figure 27.13b Conjugation and recombination in E. coli
  • Figure 27.13b Conjugation and recombination in E. coli
  • Figure 27.13b Conjugation and recombination in E. coli
  • Table 27-1
  • Figure 27.14 Metabolic cooperation in a colonial prokaryote
  • Figure 27.15 A biofilm
  • Figure 27.16 A simplified phylogeny of prokaryotes
  • Table 27.2
  • Figure 27.17 Extreme thermophiles
  • Figure 27.18 Major groups of bacteria For the Discovery Video Bacteria, go to Animation and Video Files.
  • Figure 27.18 Major groups of bacteria—proteobacteria
  • Figure 27.18 Major groups of bacteria—alpha proteobacteria
  • Figure 27.18 Major groups of bacteria—beta proteobacteria
  • Figure 27.18 Major groups of bacteria—gamma proteobacteria
  • Figure 27.18 Major groups of bacteria—delta proteobacteria
  • Figure 27.18 Major groups of bacteria—delta proteobacteria
  • Figure 27.18 Major groups of bacteria—epsilon proteobacteria
  • Figure 27.18 Major groups of bacteria
  • Figure 27.18 Major groups of bacteria—chlamydias
  • Figure 27.18 Major groups of bacteria—spirochetes
  • Figure 27.18 Major groups of bacteria—cyanobacteria
  • Figure 27.18 Major groups of bacteria—gram-positive bacteria
  • Figure 27.18 Major groups of bacteria—gram-positive bacteria
  • Figure 27.19 Impact of bacteria on soil nutrient availability
  • Figure 27.20 Mutualism: bacterial “headlights”
  • Figure 27.21 Lyme disease For the Discovery Video Antibiotics, go to Animation and Video Files.
  • Figure 27.21 Lyme disease
  • Figure 27.21 Lyme disease
  • Figure 27.21 Lyme disease
  • Figure 27.22 Some applications of prokaryotes For the Discovery Video Tasty Bacteria, go to Animation and Video Files.
  • Figure 27.22 Some applications of prokaryotes
  • Figure 27.22 Some applications of prokaryotes
  • Figure 27.22 Some applications of prokaryotes
  • Transcript

    • 1. Chapter 27 Bacteria and Archaea
    • 2.
      • Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms
      • Most prokaryotes are microscopic, but what they lack in size they make up for in numbers
      • There are more in a handful of fertile soil than the number of people who have ever lived
      Overview: Masters of Adaptation
    • 3.
      • They have an astonishing genetic diversity
      • Prokaryotes are divided into two domains: bacteria and archaea
      Video: Tubeworms
    • 4. Fig. 27-1
    • 5. Concept 27.1: Structural and functional adaptations contribute to prokaryotic success
      • Most prokaryotes are unicellular, although some species form colonies
      • Most prokaryotic cells are 0.5–5 µ m, much smaller than the 10–100 µ m of many eukaryotic cells
      • Prokaryotic cells have a variety of shapes
      • The three most common shapes are spheres (cocci), rods (bacilli), and spirals
    • 6. Fig. 27-2 (a) Spherical (cocci) 1 µm (b) Rod-shaped (bacilli) 2 µm (c) Spiral 5 µm
    • 7. Cell-Surface Structures
      • An important feature of nearly all prokaryotic cells is their cell wall, which maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment
      • Eukaryote cell walls are made of cellulose or chitin
      • Bacterial cell walls contain peptidoglycan , a network of sugar polymers cross-linked by polypeptides
    • 8.
      • Archaea contain polysaccharides and proteins but lack peptidoglycan
      • Using the Gram stain , scientists classify many bacterial species into Gram-positive and Gram-negative groups based on cell wall composition
      • Gram-negative bacteria have less peptidoglycan and an outer membrane that can be toxic, and they are more likely to be antibiotic resistant
    • 9.
      • Many antibiotics target peptidoglycan and damage bacterial cell walls
    • 10. Fig. 27-3 Cell wall Peptidoglycan layer Plasma membrane Protein Gram- positive bacteria (a) Gram-positive: peptidoglycan traps crystal violet. Gram- negative bacteria (b) Gram-negative: crystal violet is easily rinsed away, revealing red dye. 20 µm Cell wall Plasma membrane Protein Carbohydrate portion of lipopolysaccharide Outer membrane Peptidoglycan layer
    • 11. Fig. 27-3a Cell wall Peptidoglycan layer Plasma membrane Protein (a) Gram-positive: peptidoglycan traps crystal violet.
    • 12. Fig. 27-3b Cell wall Peptidoglycan layer Plasma membrane Protein (b) Gram-negative: crystal violet is easily rinsed away, revealing red dye. Outer membrane Carbohydrate portion of lipopolysaccharide
    • 13. Fig. 27-3c Gram- positive bacteria Gram- negative bacteria 20 µm
    • 14.
      • A polysaccharide or protein layer called a capsule covers many prokaryotes
    • 15. Fig. 27-4 Capsule 200 nm
    • 16.
      • Some prokaryotes have fimbriae (also called attachment pili ), which allow them to stick to their substrate or other individuals in a colony
      • Sex pili are longer than fimbriae and allow prokaryotes to exchange DNA
    • 17. Fig. 27-5 Fimbriae 200 nm
    • 18. Motility
      • Most motile bacteria propel themselves by flagella that are structurally and functionally different from eukaryotic flagella
      • In a heterogeneous environment, many bacteria exhibit taxis , the ability to move toward or away from certain stimuli
      Video: Prokaryotic Flagella ( Salmonella typhimurium )
    • 19. Fig. 27-6 Flagellum Filament Hook Basal apparatus Cell wall Plasma membrane 50 nm
    • 20. Fig. 27-6a Cell wall Filament Hook Basal apparatus Plasma membrane
    • 21. Fig. 27-6b Prokaryotic flagellum (TEM) 50 nm
    • 22. Internal and Genomic Organization
      • Prokaryotic cells usually lack complex compartmentalization
      • Some prokaryotes do have specialized membranes that perform metabolic functions
    • 23. Fig. 27-7 (a) Aerobic prokaryote (b) Photosynthetic prokaryote Thylakoid membranes Respiratory membrane 0.2 µm 1 µm
    • 24. Fig. 27-7a (a) Aerobic prokaryote Respiratory membrane 0.2 µm
    • 25. Fig. 27-7b (b) Photosynthetic prokaryote Thylakoid membranes 1 µm
    • 26.
      • The prokaryotic genome has less DNA than the eukaryotic genome
      • Most of the genome consists of a circular chromosome
      • Some species of bacteria also have smaller rings of DNA called plasmids
    • 27. Fig. 27-8 Chromosome Plasmids 1 µm
    • 28.
      • The typical prokaryotic genome is a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region
    • 29. Reproduction and Adaptation
      • Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hours
      • Many prokaryotes form metabolically inactive endospores , which can remain viable in harsh conditions for centuries
    • 30. Fig. 27-9 Endospore 0.3 µm
    • 31.
      • Prokaryotes can evolve rapidly because of their short generation times
    • 32. Fig. 27-10 EXPERIMENT RESULTS Daily serial transfer 0.1 mL (population sample) Old tube (discarded after transfer) New tube (9.9 mL growth medium) Fitness relative to ancestor Generation 0 5,000 10,000 15,000 20,000 1.0 1.2 1.4 1.6 1.8
    • 33. Fig. 27-10a EXPERIMENT Daily serial transfer 0.1 mL (population sample) Old tube (discarded after transfer) New tube (9.9 mL growth medium)
    • 34. Fig. 27-10b RESULTS Fitness relative to ancestor Generation 0 5,000 10,000 15,000 20,000 1.0 1.2 1.4 1.6 1.8
    • 35.
      • Prokaryotes have considerable genetic variation
      • Three factors contribute to this genetic diversity:
        • Rapid reproduction
        • Mutation
        • Genetic recombination
      Concept 27.2: Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes
    • 36. Rapid Reproduction and Mutation
      • Prokaryotes reproduce by binary fission, and offspring cells are generally identical
      • Mutation rates during binary fission are low, but because of rapid reproduction, mutations can accumulate rapidly in a population
      • High diversity from mutations allows for rapid evolution
    • 37. Genetic Recombination
      • Additional diversity arises from genetic recombination
      • Prokaryotic DNA from different individuals can be brought together by transformation, transduction, and conjugation
    • 38. Transformation and Transduction
      • A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called transformation
      • Transduction is the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)
    • 39. Fig. 27-11-1 Donor cell A + B + A + B + Phage DNA
    • 40. Fig. 27-11-2 A + Donor cell A + B + A + B + Phage DNA
    • 41. Fig. 27-11-3 Recipient cell B – A + A – Recombination A + Donor cell A + B + A + B + Phage DNA
    • 42. Fig. 27-11-4 Recombinant cell Recipient cell A + B – B – A + A – Recombination A + Donor cell A + B + A + B + Phage DNA
    • 43. Conjugation and Plasmids
      • Conjugation is the process where genetic material is transferred between bacterial cells
      • Sex pili allow cells to connect and pull together for DNA transfer
      • A piece of DNA called the F factor is required for the production of sex pili
      • The F factor can exist as a separate plasmid or as DNA within the bacterial chromosome
    • 44. Fig. 27-12 Sex pilus 1 µm
    • 45. The F Factor as a Plasmid
      • Cells containing the F plasmid function as DNA donors during conjugation
      • Cells without the F factor function as DNA recipients during conjugation
      • The F factor is transferable during conjugation
    • 46. Fig. 27-13 F plasmid F + cell F – cell Mating bridge Bacterial chromosome Bacterial chromosome (a) Conjugation and transfer of an F plasmid F + cell F + cell F – cell (b) Conjugation and transfer of part of an Hfr bacterial chromosome F factor Hfr cell A + A + A + A + A + A – A – A – A – A + Recombinant F – bacterium
    • 47. Fig. 27-13-1 F plasmid F + cell F – cell Mating bridge Bacterial chromosome Bacterial chromosome (a) Conjugation and transfer of an F plasmid
    • 48. Fig. 27-13-2 F plasmid F + cell F – cell Mating bridge Bacterial chromosome Bacterial chromosome (a) Conjugation and transfer of an F plasmid
    • 49. Fig. 27-13-3 F plasmid F + cell F – cell Mating bridge Bacterial chromosome Bacterial chromosome (a) Conjugation and transfer of an F plasmid F + cell F + cell
    • 50. The F Factor in the Chromosome
      • A cell with the F factor built into its chromosomes functions as a donor during conjugation
      • The recipient becomes a recombinant bacterium, with DNA from two different cells
      • It is assumed that horizontal gene transfer is also important in archaea
    • 51. Fig. 27-13-4 F factor Hfr cell (b) Conjugation and transfer of part of an Hfr bacterial chromosome A + A – F – cell A + A + A –
    • 52. Fig. 27-13-5 F factor Hfr cell (b) Conjugation and transfer of part of an Hfr bacterial chromosome A + A – F – cell A + A + A – A + A + A –
    • 53. Fig. 27-13-6 F factor Hfr cell (b) Conjugation and transfer of part of an Hfr bacterial chromosome A + A – F – cell A + A + A – A + A + A – Recombinant F – bacterium A – A +
    • 54. R Plasmids and Antibiotic Resistance
      • R plasmids carry genes for antibiotic resistance
      • Antibiotics select for bacteria with genes that are resistant to the antibiotics
      • Antibiotic resistant strains of bacteria are becoming more common
    • 55. Concept 27.3: Diverse nutritional and metabolic adaptations have evolved in prokaryotes
      • Phototrophs obtain energy from light
      • Chemotrophs obtain energy from chemicals
      • Autotrophs require CO 2 as a carbon source
      • Heterotrophs require an organic nutrient to make organic compounds
      • These factors can be combined to give the four major modes of nutrition: photoautotrophy, chemoautotrophy, photoheterotrophy, and chemoheterotrophy
    • 56. Table 27-1
    • 57. The Role of Oxygen in Metabolism
      • Prokaryotic metabolism varies with respect to O 2 :
        • Obligate aerobes require O 2 for cellular respiration
        • Obligate anaerobes are poisoned by O 2 and use fermentation or anaerobic respiration
        • Facultative anaerobes can survive with or without O 2
    • 58. Nitrogen Metabolism
      • Prokaryotes can metabolize nitrogen in a variety of ways
      • In nitrogen fixation , some prokaryotes convert atmospheric nitrogen (N 2 ) to ammonia (NH 3 )
    • 59. Metabolic Cooperation
      • Cooperation between prokaryotes allows them to use environmental resources they could not use as individual cells
      • In the cyanobacterium Anabaena , photosynthetic cells and nitrogen-fixing cells called heterocytes exchange metabolic products
      Video: Cyanobacteria ( Oscillatoria )
    • 60. Fig. 27-14 Photosynthetic cells Heterocyte 20 µm
    • 61.
      • In some prokaryotic species, metabolic cooperation occurs in surface-coating colonies called biofilms
    • 62. Fig. 27-15 1 µm
    • 63. Concept 27.4: Molecular systematics is illuminating prokaryotic phylogeny
      • Until the late 20th century, systematists based prokaryotic taxonomy on phenotypic criteria
      • Applying molecular systematics to the investigation of prokaryotic phylogeny has produced dramatic results
    • 64. Lessons from Molecular Systematics
      • Molecular systematics is leading to a phylogenetic classification of prokaryotes
      • It allows systematists to identify major new clades
    • 65. Fig. 27-16 UNIVERSAL ANCESTOR Eukaryotes Korarcheotes Euryarchaeotes Crenarchaeotes Nanoarchaeotes Proteobacteria Chlamydias Spirochetes Cyanobacteria Gram-positive bacteria Domain Eukarya Domain Archaea Domain Bacteria
    • 66.
      • The use of polymerase chain reaction (PCR) has allowed for more rapid sequencing of prokaryote genomes
      • A handful of soil many contain 10,000 prokaryotic species
      • Horizontal gene transfer between prokaryotes obscures the root of the tree of life
    • 67. Archaea
      • Archaea share certain traits with bacteria and other traits with eukaryotes
    • 68. Fig. 27-UN1 Eukarya Archaea Bacteria
    • 69. Table 27-2
    • 70.
      • Some archaea live in extreme environments and are called extremophiles
      • Extreme halophiles live in highly saline environments
      • Extreme thermophiles thrive in very hot environments
    • 71. Fig. 27-17
    • 72.
      • Methanogens live in swamps and marshes and produce methane as a waste product
      • Methanogens are strict anaerobes and are poisoned by O 2
      • In recent years, genetic prospecting has revealed many new groups of archaea
      • Some of these may offer clues to the early evolution of life on Earth
    • 73. Bacteria
      • Bacteria include the vast majority of prokaryotes of which most people are aware
      • Diverse nutritional types are scattered among the major groups of bacteria
    • 74. Fig. 27-UN2 Eukarya Archaea Bacteria
    • 75. Proteobacteria
      • These gram-negative bacteria include photoautotrophs, chemoautotrophs, and heterotrophs
      • Some are anaerobic, and others aerobic
    • 76. Fig. 27-18a Alpha Beta Gamma Delta Epsilon Proteobacteria Subgroup: Beta Proteobacteria Nitrosomonas (colorized TEM) 1 µm Subgroup: Delta Proteobacteria 10 µm Fruiting bodies of Chondromyces crocatus , a myxobacterium (SEM) Bdellovibrio bacteriophorus attacking a larger bacterium (colorized TEM) 5 µm Helicobacter pylori (colorized TEM) 2 µm 0.5 µm Subgroup: Epsilon Proteobacteria B. bacteriophorus Thiomargarita namibiensis containing sulfur wastes (LM) Subgroup: Gamma Proteobacteria Subgroup: Alpha Proteobacteria Rhizobium (arrows) inside a root cell of a legume (TEM) 2.5 µm
    • 77. Fig. 27-18b Alpha Beta Gamma Delta Epsilon Proteobacteria
    • 78. Subgroup: Alpha Proteobacteria
      • Many species are closely associated with eukaryotic hosts
      • Scientists hypothesize that mitochondria evolved from aerobic alpha proteobacteria through endosymbiosis
    • 79.
      • Example: Rhizobium , which forms root nodules in legumes and fixes atmospheric N 2
      • Example: Agrobacterium , which produces tumors in plants and is used in genetic engineering
    • 80. Fig. 27-18c Rhizobium (arrows) inside a root cell of a legume (TEM) 2.5 µm
    • 81. Subgroup: Beta Proteobacteria
      • Example: the soil bacterium Nitrosomonas , which converts NH 4 + to NO 2 –
    • 82. Fig. 27-18d Nitrosomonas (colorized TEM) 1 µm
    • 83. Subgroup: Gamma Proteobacteria
      • Examples include sulfur bacteria such as Chromatium and pathogens such as Legionella , Salmonella , and Vibrio cholerae
      • Escherichia coli resides in the intestines of many mammals and is not normally pathogenic
    • 84. Fig. 27-18e Thiomargarita namibiensis containing sulfur wastes (LM) 0.5 µm
    • 85. Subgroup: Delta Proteobacteria
      • Example: the slime-secreting myxobacteria
    • 86. Fig. 27-18f Fruiting bodies of Chondromyces crocatus, a myxobacterium (SEM) 10 µm
    • 87. Fig. 27-18g Bdellovibrio bacteriophorus attacking a larger bacterium (colorized TEM) 5 µm B. bacteriophorus
    • 88. Subgroup: Epsilon Proteobacteria
      • This group contains many pathogens including Campylobacter , which causes blood poisoning, and Helicobacter pylori , which causes stomach ulcers
    • 89. Fig. 27-18h Helicobacter pylori (colorized TEM) 2 µm
    • 90. Chlamydias
      • These bacteria are parasites that live within animal cells
      • Chlamydia trachomatis causes blindness and nongonococcal urethritis by sexual transmission
    • 91. Fig. 27-18i CHLAMYDIAS 2.5 µm CYANOBACTERIA SPIROCHETES GRAM-POSITIVE BACTERIA Chlamydia (arrows) inside an animal cell (colorized TEM) Leptospira, a spirochete (colorized TEM) 5 µm 50 µm Two species of Oscillatoria, filamentous cyanobacteria (LM ) Streptomyces, the source of many antibiotics (colorized SEM) 5 µm 1 µm Hundreds of mycoplasmas covering a human fibroblast cell (colorized SEM)
    • 92. Fig. 27-18j 2.5 µm Chlamydia (arrows) inside an animal cell (colorized TEM)
    • 93. Spirochetes
      • These bacteria are helical heterotrophs
      • Some, such as Treponema pallidum , which causes syphilis, and Borrelia burgdorferi , which causes Lyme disease, are parasites
    • 94. Fig. 27-18k Leptospira, a spirochete (colorized TEM) 5 µm
    • 95. Cyanobacteria
      • These are photoautotrophs that generate O 2
      • Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis
    • 96. Fig. 27-18l 50 µm Two species of Oscillatoria, filamentous cyanobacteria (LM )
    • 97. 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
    • 98. Fig. 27-18m Streptomyces, the source of many antibiotics (colorized SEM) 5 µm
    • 99. Fig. 27-18n 1 µm Hundreds of mycoplasmas covering a human fibroblast cell (colorized SEM)
    • 100. Concept 27.5: Prokaryotes play crucial roles in the biosphere
      • Prokaryotes are so important to the biosphere that if they were to disappear the prospects for any other life surviving would be dim
    • 101. Chemical Cycling
      • Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems
      • Chemoheterotrophic prokaryotes function as decomposers , breaking down corpses, dead vegetation, and waste products
      • Nitrogen-fixing prokaryotes add usable nitrogen to the environment
    • 102.
      • Prokaryotes can sometimes increase the availability of nitrogen, phosphorus, and potassium for plant growth
      • Prokaryotes can also “immobilize” or decrease the availability of nutrients
    • 103. Fig. 27-19 No bacteria Strain 1 Strain 2 Strain 3 Soil treatment Uptake of K by plants (mg) 0 0.2 0.4 0.6 0.8 1.0
    • 104. Ecological Interactions
      • Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont
      • Prokaryotes often form symbiotic relationships with larger organisms
    • 105.
      • In mutualism , both symbiotic organisms benefit
      • In commensalism , one organism benefits while neither harming nor helping the other in any significant way
      • In parasitism , an organism called a parasite harms but does not kill its host
      • Parasites that cause disease are called pathogens
    • 106. Fig. 27-20
    • 107. Concept 27.6: Prokaryotes have both harmful and beneficial impacts on humans
      • Some prokaryotes are human pathogens, but others have positive interactions with humans
    • 108. Pathogenic Prokaryotes
      • Prokaryotes cause about half of all human diseases
      • Lyme disease is an example
    • 109. Fig. 27-21 5 µm
    • 110. Fig. 27-21a Deer tick
    • 111. 5 µm Fig. 27-21b Borrelia burgdorferi (SEM) 5 µm
    • 112. Fig. 27-21c Lyme disease rash
    • 113.
      • Pathogenic prokaryotes typically cause disease by releasing exotoxins or endotoxins
      • Exotoxins cause disease even if the prokaryotes that produce them are not present
      • Endotoxins are released only when bacteria die and their cell walls break down
      • Many pathogenic bacteria are potential weapons of bioterrorism
    • 114. Prokaryotes in Research and Technology
      • Experiments using prokaryotes have led to important advances in DNA technology
      • Prokaryotes are the principal agents in bioremediation , the use of organisms to remove pollutants from the environment
    • 115.
      • Some other uses of prokaryotes:
        • Recovery of metals from ores
        • Synthesis of vitamins
        • Production of antibiotics, hormones, and other products
    • 116. Fig. 27-22 (a) (b) (c)
    • 117. Fig. 27-22a (a)
    • 118. Fig. 27-22b (b)
    • 119. Fig. 27-22c (c)
    • 120. Fig. 27-UN3 Fimbriae Capsule Cell wall Circular chromosome Internal organization Flagella Sex pilus
    • 121. Fig. 27-UN4
    • 122. Fig. 27-UN5
    • 123. You should now be able to:
      • Distinguish between the cell walls of gram-positive and gram-negative bacteria
      • State the function of the following features: capsule, fimbriae, sex pilus, nucleoid, plasmid, and endospore
      • Explain how R plasmids confer antibiotic resistance on bacteria
    • 124.
      • Distinguish among the following sets of terms: photoautotrophs, chemoautotrophs, photoheterotrophs, and chemoheterotrophs; obligate aerobe, facultative anaerobe, and obligate anaerobe; mutualism, commensalism, and parasitism; exotoxins and endotoxins

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