|
|
 |
|
|
|
|
|
|
 |
|
|
| |
|
|
 |
What
are germs ?
Germs are tiny organisms that can cause disease.
Germs are so small that they creep into our systems
without being noticed. In fact, germs are so tiny
that you need to use a microscope to see them.
We would not know that our body has been invaded
by them until we have symptoms of an illness.
|
|
| |
|
|
| |
|
|
|
What
Types of Germs Are There? |
|
| |
Germs are found all over the world, in all kinds
of places. There are four major types of germs:
bacteria, viruses, fungi, and protozoa. They
invade plants and animals and sometimes make us
sick. Germs invade us because they cannot live on
their own.
|
|
| |
|
|
| |
| |
|
Bacteria
|
|
| |
|
Bacteria
are tiny, single-celled creatures that get
nutrients from their environments in order
to live. In some cases that environment
is a human body. Bacteria can reproduce
outside of our bodies, or within our bodies
as they cause infections. But not all bacteria
are bad. Some bacteria are good for our
bodies - they help keep things in balance.
Examples
of bad things caused by bacteria are sore
throats, ear infections, infected cavities,
and pneumonia. "Good bacteria" live in our
intestines and help us to use the nutrients
in the food we eat and create waste products
from what's left over. We cannot make the
most of a healthy meal without these important
helper germs. Bacteria are also often used
to produce medicines and vaccines that are
genetically engineered.
|
| |
|
| |
|
|
Bacteria
consist of
only a single
cell, Bacteria
have been
found that
can live in
temperatures
above the
boiling point
and in cold
that would
freeze blood.
They "eat"
everything
from sugar
and starch
to sunlight,
sulfur and
iron.
|
|
|
|
|
|
|
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.
(Note: viruses are
not considered true
cells, so they don't
fit into either
of these categories.)
|
|
| |
|
|
|
Early
Origins
|
| |
|
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 that
make energy for your body
cells is one example of
such an organelle.
|
|
|
|
What
They Look Like
|
|
|
|
|
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.
Others are shaped
like little balls
and called cocci.
Others still are
helical or spiral
in shape, like the
Borrelia pictured
at the top of this
page. Some bacterial
cells exist as individuals
while others cluster
together to form
pairs, chains, squares
or other groupings.
|
|
Ball-shaped
Streptococci
|
|
|
| |
|
|
|
Where
They're Found
|
|
|
|
Bacteria
live on or in just
about every material
and environment
on Earth from soil
to water to air,
and from your house
to arctic ice to
volcanic vents.
Each square centimeter
of your skin averages
about 100,000 bacteria.
A single teaspoon
of topsoil contains
more than a billion
(1,000,000,000)
bacteria.
|
|
|
|
|
|
How
They Move
|
|
|
|
|
Some
bacteria move about
their environment
by means of long,
whip-like structures
called flagella.
They rotate their
flagella like tiny
outboard motors
to propel themselves
through liquid environments.
They may also reverse
the direction in
which their flagella
rotate so that they
tumble about in
one place. Other
bacteria secrete
a slime layer and
ooze over surfaces
like slugs. Others
are fairly stationary.
|
|
|
|
|
What
They Eat
|
|
|
|
Some
bacteria are photosynthetic
—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.
|
|
|
|
|
|
|
|
| |
| |
|
Viruses
|
|
| |
| |
|
Viruses
depend upon a host to survive, grow, and
reproduce. Viruses cannot live outside of
other living cells. But once they are inside
the body, viruses can spread and make people
sick. Viruses cause chicken pox, measles,
flu, and many other diseases
|
| |
| |
|
Fungi
|
|
| |
| |
|
Fungi
are multi-celled (consisting of many cells),
plant-like organisms. Unlike other plants,
fungi are not able to produce their own
food from soil, water, and air. Instead,
fungi get their nutrition from plants, food,
and animals. Fungi thrive in damp, warm
environments. Most fungi are not dangerous.
An example of something caused by fungi
is athlete's foot - that itchy rash that
teens and adults sometimes get between their
toes.
|
|
|
| |
|
Protozoa
|
|
| |
| |
|
Protozoa
are one-celled organisms like bacteria.
Protozoa also love moisture and often spread
diseases through contaminated water. Some
protozoa cause intestinal infections that
lead to diarrheoa, nausea, and stomach pain.
|
|
|
|
|
|
|
|
|
|
| |
Once
germs invade our bodies, they try to stay in for
a long stay. They consume nutrients and energy,
and produce toxins, or wastes, of their own. Those
toxins can cause symptoms of common infections
like fevers, rashes, coughing, vomiting, and diarrhea.
|
|
| |
|
|
|
How
Can You Protect Yourself From Germs? |
|
| |
-
Most
germs are spread through the air in
sneezes, coughs, or simple breaths,
or they mix and mingle in bodily fluids
like sweat, saliva, and blood. The best
way to protect yourself is to limit
those areas of contact.
-
Cover
your nose and mouth when you sneeze
and cover your mouth when you cough
to keep from spreading germs.
|
|
| |
|
|
|
-
And
remember the two words germs that fear
- soap and water. Washing your hands
well and often is the best way to keep
them away. Wash your hands every time
you cough or sneeze, before and after
you prepare foods or use the toilet,
after you handle money, and after you
visit a sick relative or friend.
-
Using tissues to contain your sneezes
and sniffles is another good way to
protect oneself great weapon against
germs. But don't just toss tissues on
the floor to pick up later. Toss them
in the waste bins and again, wash your
hands!
|
|
|
| |
Bacteria that cause
foodborne illness
|
|
| |
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
