· Many of us know bacteria only as “germs,” invisible creatures that can
invade our bodies and make us sick.
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Few know that many bacteria not only
coexist with us all the time, but help us do an amazing array of useful things
like make vitamins, break down some garbage, and even maintain our atmosphere.
·
Bacteria consist of only a single cell,
but don't let their small size and seeming simplicity fool you. They're an
amazingly complex and fascinating group of creatures. Bacteria have been found
that can live in temperatures above the boiling point and in cold that would
freeze your blood. They "eat" everything from sugar and starch to
sunlight, sulfur and iron. There's even a species of bacteria—Deinococcus radiodurans—that can withstand blasts of
radiation 1,000 times greater than would kill a human being.
·
Bacteria fall into a category of life
called the Prokaryotes (pro-carry-oats). 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 (you-carry-oats), creatures
whose cells have nuclei.
·
(Note: viruses are not considered true
cells, so they don't fit into either of these categories.)
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Does a bacterium’s cell wall,
shape, way of moving, and environment really matter?
·
Yes! The more we know about
bacteria, the more we are able to figure out how to make microbes work for us
or stop dangerous ones from causing serious harm. And, for those of us who like
to ponder more philosophical questions like the origins of the Earth, there may
be some clues there as well.
· Bacteria and their microbial cousins the archaea were
the earliest forms of life on Earth. And may have played a role in shaping our
planet into one that could support the larger life forms we know today by
developing photosynthesis.
Cyanobacteria fossils date back more than 3 billion years. These photosynthetic bacteria paved the way for today's algae and plants. Cyanobacteria grow in the water, where they produce much of the oxygen that we breathe. Once considered a form of algae, they are also known as blue-green algae.
Bacteria are among the earliest forms of life that appeared on Earth billions of years ago. Scientists think that they helped shape and change the young planet's environment, eventually creating atmospheric oxygen that enabled other, more complex life forms to develop. Many believe that more complex cells developed as once free-living bacteria took up residence in other cells, eventually becoming the organelles in modern complex cells. The mitochondria (mite-oh-con-dree-uh) that make energy for your body cells is one example of such an organelle.
Cyanobacteria fossils date back more than 3 billion years. These photosynthetic bacteria paved the way for today's algae and plants. Cyanobacteria grow in the water, where they produce much of the oxygen that we breathe. Once considered a form of algae, they are also known as blue-green algae.
Bacteria are among the earliest forms of life that appeared on Earth billions of years ago. Scientists think that they helped shape and change the young planet's environment, eventually creating atmospheric oxygen that enabled other, more complex life forms to develop. Many believe that more complex cells developed as once free-living bacteria took up residence in other cells, eventually becoming the organelles in modern complex cells. The mitochondria (mite-oh-con-dree-uh) that make energy for your body cells is one example of such an organelle.
·
There are thousands of species of
bacteria, but all of them are basically one of three different shapes.
Some are rod- or stick-shaped and called bacilli (buh-sill-eye).
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Others are shaped like little balls
and called cocci (cox-eye).
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Others still are helical or spiral
in shape, like the Borrelia pictured
at the top of this page.
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Some bacterial cells exist as
individuals while others cluster together to form pairs, chains, squares or
other groupings.
· Some bacteria are photosynthetic (foe-toe-sin-theh-tick)— they can make their own food from sunlight, just
like plants. Also like plants, they give off oxygen. Other bacteria absorb food
from the material they live on or in. Some of these bacteria can live off
unusual "foods" such as iron or sulfur. The microbes that live in
your gut absorb nutrients from the digested food you've eaten.
·
Bacteria can be
found virtually everywhere. They are in the air, the soil, and water, and in
and on plants and animals, including us. A single teaspoon of topsoil contains
about a billion bacterial cells (and about 120,000 fungal cells and some 25,000
algal cells). The human mouth is home to more than 500 species of bacteria. ome bacteria (along with archaea) thrive in the
most forbidding, uninviting places on Earth, from nearly-boiling hot springs to
super-chilled Antarctic lakes buried under sheets of ice. Microbes that
dwell in these extreme habitats are aptly called extremophiles.