Docstoc
EXCLUSIVE OFFER FOR DOCSTOC USERS
Try the all-new QuickBooks Online for FREE.  No credit card required.

Bacteria

Document Sample
Bacteria Powered By Docstoc
					             Bacteria
 Questions you need to be able to
             answer:
• What are bacteria?
• How do bacteria affect the human
  body?
• How are bacteria prevented and
  treated?
• How do bacteria reproduce?
• Bacteria are prokaryotic unicellular
  organisms
• Different types of bacteria have different
  shapes which are often used in their
  names.
• Possible shapes:
  – Bacillus (rod like)
  – Coccus (sphere like)
  – Spirillum (spiral like)

• Example: streptococcus (strep throat)
            Bacterial Counts
•    There are typically:
    – 40 million bacterial cells in a gram of soil
    – 1 million bacterial cell in a milliliter of fresh
      water
    – In all, there are approximately five nonnillion
      (5x1030) bacteria in the world.
    – There are approximately 10 times as many
      bacterial cells as human cells in the human
      body, with large numbers of bacteria on the
      skin and in the digestive tract.
          Bacterial Division
• Bacteria reproduce by a process called
  binary fission in which they make an
  identical copy of themselves.

• Under optimal conditions, bacteria can
  grow and divide extremely rapidly.
  – Bacterial populations can double as quickly as
    every 9.8 minutes
            Endospores
• Bacteria can form endospores which are
  highly resistant, dormant structures.

  – In the dormant state these organisms may
    remain viable for millions of years.

  – Endospores are so resilient that they can
    survive exposure to a vacuum or radiation in
    space.
• 99% of bacteria are helpful or do no harm
  to us.

• About 1% of bacteria are pathogenic
  (meaning they cause disease).

  – Cholera, syphilis, anthrax, leprosy, and
    bubonic plague are all caused by bacteria.
           Bacterial Infections
• Bacteria enter the body because the body
  offers an environment that the bacteria
  can flourish in.

• Pathogenic bacteria generally enter the
  body and begin reproducing.

• The damage they cause can be due to
  toxins released by the bacterial cells, or by
  bacterial cells actually entering body cells.
   Treating Bacterial Infections
• Antibiotics are used to treat bacterial infections.

• Antibiotics affect different bacteria in different
  ways. They could:

   – inhibit a bacterium's ability to turn glucose into energy
   – Inhibit a bacterium’s ability to construct its cell wall.


• Avoiding exposure can prevent infections.
                Viruses
    Questions you need to be able to
                answer:
•   What are viruses?
•   How do viruses affect the human body?
•   How do viruses reproduce?
•   How are viruses prevented and
    treated?
• Viruses are non-living pathogens that
  consist of genetic materials (DNA or RNA)
  surrounded by a protective coat of protein.

• Since viruses are non-living, they are
  unable to reproduce on their own, and
  instead need to invade a host cell and
  force it to make new viruses.

• Viruses generally follow one of two
  pathway
Lytic cycle
• The virus invades a cell and replaces the
  cell’s genetic material with its own.

• The cell then begins producing virus
  particles instead of what it was producing
  before

• Eventually the cell bursts oopen (lyses)
  and the new virus particles are released.
Lysogenic cycle
• The virus invades a cell and adds its own
  genetic material to the cell so that when
  the cell divides all of the new cells get the
  viral geneitc material as well.

• The virus remains dormant but after some
  time the virus will become active and enter
  the lytic cycle.
Treatment of Viruses
• Antibiotics DO NOT work on viral
  infections.

• Often vaccinations are created in which a
  weakened or dead form of the virus is
  introduced to the body.

• The body then fights the virus and
  remembers how it won, so that if it ever
  gets infected again the virus will be
  destroyed quickly.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:35
posted:9/28/2011
language:English
pages:14