B a c t e r i a

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B a c t e r i a
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Characteristics

• Bacteria are smallest living organisms
• Bacteria consist of a single cell
• Bacteria are nearly 3.5 billion years old. They
  are among the earliest forms of life that
  appeared on Earth.
  

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Bacterial Cell

• Bacterial cells are prokaryotic they have
• no nucleus or other membrane-bound
  organelles
  
• Bacterial cells have a single chromosome a
  circular DNA molecule
  
• Bacterial cells have a cell wall
• Most bacteria reproduce by binary fission

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Classification

• Bacteria fall into a category of life called the
  Prokaryotes. Prokaryotes' genetic material, or
  DNA, is not enclosed in a cellular compartment
  called the nucleus.
• Bacteria and archaea are the only prokaryotes.
  All other life forms are Eukaryotes, creatures
  whose cells have nuclei.
  

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What they look like?

• There are thousands of species of bacteria, but
  all of them are basically one of three different
  shapes.

• 3. Spirilla are helical or spiral in shape

• Cocci are shaped like little balls

• 2. Bacilli are rod- or stick-shaped

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What they eat?

• Autotrophs
• photosynthetic bacteria can make their own
  food from carbon dioxide using sunlight, just
  like plants.
  
• chemosynthetic bacteria produce their own
  organic compounds from inorganic substances such
  as iron or sulfur.
  
• Heterotrophs
• needs organic substances that have already
  been assembled by autotrophs.

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Where they live?

• Bacteria live just about everywhere in the soil,
  water and air in animals, plants, rocks and even
  in us!
  

Bacteria from boiling water of hot springs in Ye
llowstone National Park
Bacteria on our teeth
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Spores

• Spore (or endospore) is a dormant cell. It has a
  tough shell that insulates and protects the
  genes and basic cell parts.
  
• Spores are resistant to heat and cannot be
  readily destroyed, even by boiling.
  
• In 2000, scientists revived bacteria that had
  lain in suspended animation for 250 million
  years.

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Role of bacteria

• Negative
• Bacteria can cause illnesses
• Diarrhea
• Lyme disease
• Botulism
• Leprosy
• How can you protect yourself and others from
  contamination by pathogenic bacteria?

Wash up!
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Role of bacteria, cont.

• Positive
• There are many important jobs bacteria do.
• They are used to make medicine.
• They break down oil from oil spills.
• They make about half of the oxygen we breath.
• They are the foundation of the food chain that
  feeds all life on earth

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Our Friends
Bacteria do many good thins for us
Escherichia coli one of many kinds of microbes
that live in your gut. Wanted for helping you
digest your food every day.
Pseudomonas putida one of many microbes wanted
for cleaning wastes from sewage water at water
treatment plants.
Streptomyces soil bacteria wanted for making
streptomycin, an antibiotic used to treat
infections.
Lactobacillus acidophilus one of the bacteria
gang wanted for turning milk into yogurt.
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Questions

• What kind of medication are antibiotics?
• Why it is necessary to boil water before
  drinking?
  
• Why hospitals sterilize instruments in
  autoclaves?
  
• Escherichia coli is a normal resident of the
  mammalian gut. What is its role?
  
• Can bacteria sense and move?
• What are the cell shapes of Lactobacillus,
  Staphylococcus, Spirochaeta?
  

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Answer 1

• Antibiotics fight diseases that are caused by
  bacteria.
  
• Bacteria are constantly changing and developing
  antibiotic-resistant strains.
  
• We need new antibiotics that can fight resistant
  strains of bacteria.

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Answer 2

• Drinking-water may be contaminated by a range of
  microbes that may pose risks to health
  
• 1.8 million people die every year from diarrheal
  diseases (including cholera) 90 are children
  under 5, mostly in developing countries.
  
• High temperature kills the majority of pathogenic
  bacteria
  

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Answer 3

• Boiling temperature is not enough to kill
  bacteria spores.
  
• An autoclave is designed to produce temperatures
  and pressures that will completely sterilize
  objects.

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Answer 4

• E.coli
• enhances digestion
• Impedes colonization of the gut by a variety of
  pathogens
  
• Can cause diarrhea (E.coli is the leading cause
  of infant mortality for most of the human
  population)

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Answer 5

• Bacteria sense light, detect the presence of
  oxygen and other chemical compounds.
  Magnetotactic bacteria have a chain of magnetite
  particles in their cytoplasm that serves as a
  tiny compass.

Some bacteria move about their environment by
means of long, whip-like structures called
flagella.
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Answer 6

• Lactobacillus
• Staphylococcus
• Spirochaeta

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Interesting facts about bacteria

• Bacteria can live in temperatures above the
  boiling point and in cold that would freeze your
  blood. There's even a species of
  bacteriaDeinococcus radioduransthat can
  withstand blasts of radiation 1,000 times greater
  than would kill a human being.
• They "eat" everything from sugar and starch to
  sunlight, sulfur and iron.

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Biggest Bacterium

• The colossus among bacteria is a single-celled
  giant that lives in the ocean and is named
  Thiomargarita namibiensis , which means "sulfur
  pearl of Namibia." It was found in the ocean
  floor off the coast of Namibia in Africa. T.
  namibiensiss ball-shaped cells can grow to
  almost 1 millimeter or 1/25th of an inch in
  diameter. Thats about as big as the period at
  the end of a sentence.

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Millions of them

• Your body is home to trillions of microbes. Run
  your tongue over your teethyou're licking
  thousands of microbes that normally live on your
  teeth. Millions of them live on your tongue, too.
  A large part of "you" (that is, the mass of your
  body) is actually something else bacteria,
  viruses and fungi. Isn't that a weird thought?
• A single teaspoon of that soil contains over
  1,000,000,000 bacteria,

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Bacteria on Mars?

• Some scientists even believe there is the
  possibility bacteria may have once lived on Mars.
  This photograph shows what some scientists
  believe may be the fossils of tiny bacteria in a
  rock that formed on Mars about 4.5 billion years
  ago.

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Find more interesting facts about bacteria