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					Bacteria

Chapter 19.1
                   Prokaryotes
• Unicellular organism lacking a nucleus.
  – Very tiny
  – Commonly referred to as bacteria
• Classified under the Kingdom called Monera
  – Split into two domains
     • Eubacteria
     • Archaebacteria
              Comparing Domains
Eubacteria                        Archaebacteria
• Variety of Lifestyles           • Lives in extreme
   – Lives in many environments     environments
• Cell Wall (Has Peptidoglycan    • Cell Wall (Has no
  in it)                            Peptidoglycan)
• No Nucleus                      • Has unique lipids
• May have multiple cell          • No nucleus
  membranes                       • Gene similar to eukaryotes
         4 Ways to Classify Them
• Classify based on……
  1.   Shape
  2.   Chemistry of Cell Wall
  3.   Movement Types
  4.   Metabolic Pathways
          Describe the Shapes


Bacilli        Cocci            Spirilla




Rod-shaped     Sphere-shaped
                                Spiral-shape
                Cell Wall Contents
         Eubacteria
Gram-positive    Gram-negative   Archaebacteria




Thick            Thin            No
Peptidoglycan    Peptidoglycan   Peptidoglycan
Cell Wall        Cell Wall       Cell Wall
                Movement Types
• Bacteria move in a number of different ways.
  – Here are some of, but not limited to, these ways.
     •   No movement
     •   Spiral or corkscrew
     •   Using Flagella
     •   Secreting slimy substance
             Metabolic Pathways
• Classified into different categories by 2 principles
  – How they obtain energy
  – If they need oxygen
                  Obtaining Energy
                       Heterotrophs
• Organisms that need to ingest some type of food
   – Chemoheterotroph: organism that ingests to
     get both energy and organic substances




   – Photoheterotroph: organism that uses
     photosynthesis to get energy, but needs to
     ingest food to obtain carbon compounds
               Obtaining Energy
                     Autotrophs
• Organism that creates their own
  food
  – Photoautotroph: uses energy from the
    sun to create carbon compounds they
    need for food

  – Chemoautotroph: uses energy from
    chemical reactions to create
    necessary carbon compounds
         Oxygen Dependence
     (used to breakdown gathered energy)
• Obligate Aerobe:
  – Needs oxygen to survive; will die without it


• Facultative Anaerobe
  – Can live with or without oxygen


• Obligate Anaerobe
  – Cannot live in oxygen; will die if present
          Growth and Reproduction
• Very fast reproduction. Some reproduce every
  20 minutes
  – Is controlled by limited resources


• 1) Binary Fission
  – Follows asexual reproduction 2 Stages
     • 1) DNA replication
     • 2) Cell divides into two new bacteria
        – Mitosis
               Conjugation
• Genetic variation for bacteria
• Bacteria share some genetic info
  by transferring it
• Work by….
  – Forming a connective bridge
  – Gene sharing occurs using bridge
  – Bacteria reproduce
• Adds new variation to
  population
                   Endospore
• Bacteria protective covering
  – When environmental conditions become harsh,
    endospores form
  – Thick, internal wall surrounds DNA and some
    cytoplasm for later use
  – Returns to bacterial state when conditions
    favorable
         Importance of Bacteria
• Atmosphere
  – Most organisms need oxygen to survive
  – Photosynthetic bacteria produce oxygen in the air
    and water.


• Decomposers
  – Decomposition: the breakdown of dead organisms
  – Recycles needed nutrients back into environment
     • Without this, nutrients would get used up
              More Bacteria Uses
• Nitrogen Fixers
  – Nitrogen gas is abundant in atmosphere, but is
    useless to organisms
  – Bacteria turn nitrogen gas into more useable
    nitrogen compounds
     • Bacteria live in plant roots
     • Symbiosis with plants (both benefit)
   Human Uses
• Help to make food and drink
• Industry
  – Used to clean oil spills
  – Waste product removal
• Intestines: help breakdown food and make
  vitamins needed by body
  – Symbiotic relationship
• Genetic Engineering: inject bacteria using plasmid
  (DNA ring)
  – Can be used to make antibiotics and proteins needed

				
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