Docstoc

Kingdom Eubacteriaand Archeabacteria

Document Sample
Kingdom Eubacteriaand Archeabacteria Powered By Docstoc
					Kingdom Eubacteria and
Kingdom Archaebacteria
        Characteristics of Bacteria
Bacteria are by far the most abundant organisms on Earth.
As a group they are very diverse, but they all share certain
   characteristics.
1. All bacteria are single-celled.
2. All bacteria are prokaryotes:
     Their DNA is not surrounded by a membrane.
      Cell organelles in bacteria are not surrounded by
         membranes.
3. The DNA of bacteria is made of a single chromosome.
4. All bacteria reproduce asexually by binary fission.
                        Bacteria
• As a group, bacteria are the smallest organisms.
• They are usually 1–10 microns
• A typical eukaryotic cell is about 10 times larger.
          Structure of a Bacteria
• The structure is simple:
• Cell wall: provides support and protection for the
  contents of the cell.
• Cell membrane controls the passage of materials into
  and out of the cell.
• The cytoplasm contains ribosomes, responsible for the
  formation of proteins
• The DNA is a single chromosome formed into a ring
• There is roughly 1/1000th the amount of DNA than in a
  typical eukaryotic cell.
   Projections Provide Locomotion
• Some bacteria have whip-like flagella (singular:
  flagellum).
• They act like propellers moving in reverse, drawing the
  organism forward.
• Some bacteria have cilia (also called pili), tiny hair-like
  structures on the surface of the cell
• They beat to move the bacteria forward
                          Cell shape
• spherical cell is called a coccus (pural: cocci)
• a rod shaped cell is called a bacillus (plural: bacilli)
• a spiral-shaped cell is called a spirillum (plural: spirilli).
                      More names
• monococci: cocci that live as separate cells
• Diplococci: cocci that live in pairs.
• Streptococci: cocci that live in linear chains
•  Staphlococci: cocci that live in grapelike clusters
• Bacilli also exist as single cells, pairs (diplobacilli), or
  chains (streptobacilli).
• Spiralbacteria exist only as single cells.
                      Nutrition
• There is a large variety of nutritional patterns among
  bacteria.
                     Respiration
• All living things must carry out cellular respiration to
  receive a supply of energy for life’s functions.
• Bacteria differ in whether or not they require oxygen.
                    Respiration
• If cellular respiration involves oxygen to produce energy,
  bacteria are termed aerobes.
• If oxygen is absolutely necessary for their survival, they
  are called obligate aerobes.
• Those bacteria that can carry out cellular respiration in
  an oxygen-free environment are termed anaerobes.
• If the presence of oxygen kills these organisms, they are
  called obligate anaerobes.
• A third group of bacteria can survive with or without
  oxygen and they are called facultative anaerobes.
                  Reproduction
• All bacteria reproduce asexually and divide
  by the process of binary fission
                  Reproduction
• Bacteria can reproduce in 15 to 20 minutes as long as
  there is sufficient food, warmth, and space.
• Under the right conditions, a single E.coli bacterium can
  produce between 10 and 100 million bacteria in 12
  hours.
 Conjugation- sexual reproduction
• During conjugation, two bacterial cells connect to each other
  by long protein bridges
• The plasmid (ring of extra DNA) of one cell is transferred to
  the other cell.
• When the process is completed, the bacterium that received
  the genetic material from the other cell now has a different
  genetic makeup
• Having an altered genetic makeup increases the chance that a
  bacterium might possess a gene combination that enables the
  organism to adapt to worsening conditions.
            Bacteria and Disease

• Only a small percentage of prokaryotes are pathogenic,
  or disease causing.
• Pathogenic bacteria produce deadly substances (toxins)
  in the human body that cause disease symptoms.
    The Two Kingdoms of Bacteria
• There are two kingdoms of bacteria:
   – Archaebacteria in the domain Archea
   – Eubacteria in the domain Bacteria
Achaebacteria
                Archaebacteria
• Most archaebacteria live in extreme environments. These
  are called extremophyles.
• Other Archaebacteria species are not extremophiles and
  live in ordinary temperatures and salinities. Some even
  live in your guts!
                    Archaebacteria
• Some extremophile species love the heat! They like to live in boiling
  water, like the geysers of Yellowstone Park, and inside volcanoes.
• These are called "thermophiles" which means "loving heat", and it
  would probably freeze to death at ordinary room temperature.
• Other extremophile Archaea live in very salty, called hypersaline,
  environments. These salt-loving Archaea are called halophyles.
• Other achaea are known as methanogens.
• Methanogens are methane producers. Most of these bacteria use
  carbon dioxide as their carbon source. They are found in soil,
  swamps, and most animals digestive tracts
                     Eubacteria
• Eubacteria are more common and more widespread than
  acheabacteria.
• There are typically 40 million bacterial cells in a gram of
  soil and a million bacterial cells in a millilitre of fresh
  water
• There are approximately five nonillion (5×1030) bacteria
  on Earth, forming much of the world's biomass.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:7
posted:12/3/2011
language:English
pages:22