Bacteria

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Bacteria

• Prokaryotic Cells

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General Description

• Single celled prokaryote
• 1-10 micrometer (1/10 of a cell)
• Kingdom Eubacteria or Archeobacteria

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Eubacteria

• Largest group. Wide variety of habitats and
  behaviors
• Found in every environment (including your
  intestinal tract)

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Archaeobacteria

• Live in harsh environments oxygen free, salt
  lakes, hot geysers, or deep ocean vents

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Identifying bacteria

• Shape rod- bacilli, sphere- cocci, spiral-
  spirilla,
• Shapes part of name streptococcus, pneumococcus

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Cell Wall

• Classification based on thickness
• Gram positive- absorb and retain crystal violet
  stain
• Sensitive to penicillin, interferes with protein
  synthesis, weakens cell wall

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Gram Negative

• Dont pick up stain
• Cell wall makes bacteria resistant to hypotonic
  conditions. In hypertonic they will dehydrate.
• Salt curing or sugar curing used to preserve food

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Capsule

• Capsule many have a slime capsule which helps
  them evade phagocytosis by white blood cells.
  Allows them to stick to surface (teeth)

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Movement

• Some bacteria have flagella and can move
• Ex bacteria that cause cholera

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DNA

• Bacteria have circular DNA and extra fragments
  called plasmids
• Plasmids can reproduce separately

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Endospores

• dormant state of bacteria
• Transform into spores to withstand unfavorable
  conditions- dont dry up and shrink.
• Survive 1 hour in boiling water, centuries of
  freezing, dry conditions

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Endospores

• Sterilization is crucial to surgical instruments
• Anthrax has been converted into endospores and
  therefore is a biological weapon threat

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Energy

• Varied methods of obtaining energy
• Autotrophs- make own energy
• Phototroph- Use photosynthesis
• Chemotroph- change chemicals such as hydrogen
  sulfide into sugar. Rare

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Energy

• Heterotroph- obtain energy thru other sources
• Chemotroph hetertroph- get energy from organic
  compunds
• Phototrophic heterotroph- do both, make own and
  consume

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Respiration Needs

• Obligate aerobes require oxygen
• Obligate anaerobes must not have oxygen
• Facultative anaerobes- dont need oxygen but can
  tolerate it

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Anaerobes

• Botulism- caused by bacteria which need no
  oxygen- in canned food
• Cause nerve paralysis
• Canning must be done properly, no air space,
  sterile

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Reproduction

• Incredibly rapid- 1 bacterium can divide into two
  in 20 min.
• Two methods
• Binary fission- splits in
  2. Asexual.
• Offspring clones.

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Conjugation

• Exchange genetic info- form temp. cytoplasmic
  bridge
• Offspring genetics different
• Allows bacteria to survive environmental change
  and adapt and survive

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Reproduction

• Builds resistance to antibiotics or antiseptics
• Penicillium

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Reproduction rate

• Time required for new generation to form
  (generation time)
• Varies between species range between 10 minutes
  and several hours

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Reproduction rate

• Every bacterium is doubling- growth is described
  as exponential.
• Slope of growth rate increases dramatically

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Exponential Growth