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What characteristics make Archaea more like eukaryotes than prokaryotes

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Bacilli. Spirilla. Cell Wall. What are the functions of the cell wall in prokaryotes? ... Endospore forming bacteria Bacillus. Mycoplasmas- smallest bacteria, ... – PowerPoint PPT presentation

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Title: What characteristics make Archaea more like eukaryotes than prokaryotes


1
What characteristics make Archaea more like
eukaryotes than prokaryotes?
  • No peptidoglycan in cell wall
  • More than 1 RNA polymerase
  • Some introns
  • Met is 1st amino acid in protein synthesis
  • Ribosomes more like eukarytoes (Streptomycin does
    not kill archaea)

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More recent studies revealed that archaebacteria
is not monophyletic
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Diversity of prokaryotes
http//genomics.ucla.edu/eocyte/bluinsert2.gif
5
Morphology
  • Cocci
  • Bacilli
  • Spirilla

6
Cell Wall
  • What are the functions of the cell wall in
    prokaryotes?
  • Maintain cell shape
  • Protection
  • Prevent bursting in hypotonic environment
  • Made of peptidoglycan
  • Why is some food preserved by salting it?
  • Hypertonic environment plasmolyzes bacterial cells

7
Cell Wall Structure
  • What is the composition of prokaryotic cell
    walls?
  • Peptidoglycan
  • Exact components vary among species
  • Some antibiotics work by preventing formation of
    cross-links in peptidoglycan

8
Gram/Gram-
  • Gram positive bacteria
  • Stains blue/violet
  • Simple cell walls with lots of peptidoglycan
  • Purple/blue stain is trapped in cell wall
  • Less threatening pathogens tooth decay, strep
    throat
  • Gram negative bacteria
  • More complex cell walls with less peptidlglycan
  • Blue dye washes out so they stain pink (first
    dye)
  • Outer membrane covers cell wall
  • More pathogenic than gram typhus gonorrhea
  • Lipopolysaccharides in outer membrane often toxic

9
Adherence
  • Capsule
  • Gelatinous secretion that helps cell adhere to
    host
  • Pili
  • Surface appendages used for conjugation or
    adherence to host

10
Bacterial Movement
  • Flagella
  • Spirochetes move via axial helical filaments
  • Glide via slimy chemical secretion
  • Many are capable of taxis in heterogenous
    environment

11
Basic Cell
  • What does the basic prokaryotic cell look like?
  • Nucleoid region one circular piece of DNA
  • Specialized membranes provide metabolic functions
  • Little protein associated with bacterial genome
  • Bacterial ribosomes differ from eukaryotic
    ribosomes
  • Allows antibiotics such as tetracycline to
    destroy bacterial cells and not eukaryotic cells

12
Reproduction
  • Binary fission, no mitosis or meiosis
  • What are the methods of genetic recombination?
  • Transformation
  • Conjugation
  • Transformation
  • Mutations
  • What are endospores?

13
Metabolic Diversity
  • What are the four possible modes of bacterial
    nutrition?
  • Photoautotrophs
  • Chemoautotrophs
  • Photoheterotrophs
  • Chemoheterotrophs most bacteria are in this
    group

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Metabolic Relation to Oxygen
  • How are bacteria categorized by the effect that
    oxygen has on growth?
  • Obligate aerobes
  • Facultative anaerobes
  • Obligate anaerobes
  • What role do prokaryotes play in nitrogen
    cycling?
  • Only way that nitrogen gas can be incorporated
    into organic molecules

16
Origins of Metabolic Diversity
  • Heterotrophs most likely came before
    photoautotrophs (parsimony)
  • Glycolysis was probably the first metabolic
    pathway
  • Natural selection favored autotrophs as
    heterotrophs depleted food supply
  • Cyanobacteria introduce chl a and oxygen gas.

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Importance
  • Chemical cycling, decomposers
  • Symbiotic relationships
  • Use in DNA technology
  • Digest sewage and oil spills
  • Convert milk to yogurt and cheese

19
Disease
  • Disease
  • exotoxins release poisons such as botulism and
    cholera
  • Endotoxins seen in outer membrane of gram neg.
    bacteria (Salmonella)
  • What are Kochs postulates and why are they
    important?
  • Kochs postulates used to isolate pathogen
    causing disease

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Three Groups
  • Methanogens
  • Extreme halophiles
  • Extreme thermophyles - eocytes

23
Eubacteria
  • Proteobacteria
  • Purple bacteria use H2S as electron source do not
    release oxygen
  • Chemoautotrophic free living chemical cycling
    role, example Rhizobium in root nodules of
    legumes (formerly nitrogen fixing bacteria now
    alpha proteobacteria)
  • Gamma proteobacteria autotrophic and
    heterotrophic, use H2S as source of electrons,
    includes enteric bacteria e.g. E. coli and
    Salmonella

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  • Gram Positive Bacteria (some are not)
  • Endospore forming bacteria Bacillus
  • Mycoplasmas- smallest bacteria, lack cell walls
  • Actinomycetes, found in soil, resemble fungi,
    e.g. Streptomyces source of antibiotics
  • Cyanobacteria photoautotrophs with chla, some
    have heterocysts for nitrogen fixation, examples
    Oscillatoria, and Anabaena
  • Spirochetes helical heterotrophs e.g. syphilis
  • Chlamydias parasites of animals, gram neg. cell
    walls, cause chlamydia STD and typhus

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Germinating akinetes
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Stains violet/blue
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Are these bacteria Gram or Gram ?
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Aerobic porkaryote
Photosynthetic prokaryote
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