Introduction to Bacteria

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Chapter 21.2

• Introduction to Bacteria

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Monerans

• Now divided into two separate Kingdoms
• Archaea
• Bacteria
• Very different
• Cell walls
• Sequence of bases
• React differently to antibiotics

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Archaea

• Earliest Monerans
• Live in extreme habitats
• Oxygen-free environments, produce methane
• Concentrated salt water
• Hot, acidic waters of sulfur springs

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Bacteria

• Wide array of habitats and metabolism
• Heterotrophs
• Photosynthetic autotrophs
• Chemosynthetic autotrophs

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Heterotrophs

• Need organic molecules as an energy source
• Not adapted for trapping the food that contains
  those molecules
• Parasites absorb nutrients from living organisms
• Saprobes feed on dead organisms or organic waste

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Photosynthetic Autotrophs

• Obtain their energy from sunlight
• Cyanobacteria
• Composed on chains of cells
• Contain chlorophyll a
• Prochloron contains chlorophylls a and b

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Chemosynthetic Autotrophs

• Obtain energy from the chemosynthetic breakdown
  of inorganic substances
• Sulfur compounds
• Nitrogen compounds
• Important to convert nitrogen in atmosphere to
  forms that can be used by plants

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Cellular Structure

• Monerans smallest and simplest living things
• No membrane bound organelles
• Small ribosomes
• Genetic material held in a single, circular
  chromosome

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Typical Bacterial Cell

• Flagella long, whiplike structures, enable the
  cell to move
• Pili hairlike structures, help bacteria to stick
  to surfaces or each other
• Plasma membrane controls what goes in and out of
  the cell
• DNA single, circular chromosome contains all
  genetic information
• Cell wall rigid, gives cell shape, prevents
  osmotic rupture
• Capsule gelatinous, cant be engulfed by white
  blood cells as easily

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Bacterial Cell Structure
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Classified by Shape

• Spheres Coccus
• Rods Bacillus
• Spirals Spirilium

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Classified by their arrangements

• Diplo cells are paired
• Staphylo grapelike clusters
• Strepto long chains

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Penicillin

• Bacterial cell walls are made of sugars linked by
  short chains of amino acids
• This forms a strong cell wall which prevents
  osmotic rupture
• Many bacteria live in hypotonic environments
• Penicillin acts by interfering with the enzyme
  that links sugar chains in the cell wall
• This causes holes to be left in the cell wall
• Therefore, when water enters the bacterial cell,
  the cell ruptures and dies
• Penicillin is non-toxic to plants, animals and
  viruses