A
bacterium ("back-tear-ee-um") is a very tiny living thing-too
small to see with the naked eye. The sizes of bacteria (the
plural of bacterium) are measured in micrometres - 10 000 micrometres
= 1 centimetre! The head of a steel pin is about 1000 micrometres
wide!
There are a lot of different bacteria found nearly everywhere
in the world, but only a few are harmful to humans or animals.
Many other bacteira are very important for life on Earth.
Because bacteria have quite simple lifecycles, scientists have
been able to study the way they live and grow and have learned
that most of the basic chemistry in all living things is the
same.
So Where Are They?
As soon as a baby is born it comes into contact with bacteria.
Many of these live in the baby's intestine (gut), and as the
baby grows, bacteria begin to live on the skin and other parts
of the body. These bacteria are called "Normal Flora" - they
exist in and on your body and, while you are healthy, don't
cause any sickness. In fact, they often help you, for example,
the bacteria in your gut help you to digest your food. Other
animals have bacteria in their guts, but because their normal
flora are often different from ours, they can make us sick.
Dog droppings are a common way for young children to pick up
these bacteria..
Bacteria can be spread to humans from:
-
Other humans (from sneezing or coughing)
-
Animals (by droppings or saliva)
-
Soil (normally contain fungi; when contaminated by droppings)
-
Water (when contaminated by droppings)
What
Is A Germ?
The word germ actually means any microorganism
(small living thing). This includes a virus, a fungus or a bacterium.
What Do They Look Like?
Bacteria can be commonly found in rodlike, spherical or corkscrew
shapes and can be seen as single cells or as pairs, chains or
clusters. Bacterial cells are very different from human cells
in a couple of ways:
-
The bacterial cells have a wall,
-
The nucleus (the area of the cell where all the genes are
stored) of the bacterial cell does not have a special membrane
to seperate it from the rest of the cell.
All
the different types of bacteria have been grouped to make identification
easier. These groupings or "Divisions" are then grouped a bit
more into "Classes", which are divided into "Orders", orders are
further grouped into "Families" and families grouped into "Genera"
(jen-er-a) and genera into "Species" (spee-sheez). A bacterial
species is a group of cells which are very similar to each other.
So
what?
This system of grouping allows scientists to carefully name
any newly found bacterium so that it won't be confused with
known bacteria. These names have a first (the genus) and last
(species) name just like we do. But they are a bit harder to
spell! Because there are two parts to the name, the naming system
is called a "Binomial" (bye-no-meal) system.
For example:
Escherichia (esh-er-ishia) coli (col-eye)
- see what I mean about spelling?
This is very similar to the grouping system that humans are
a part of. For example:
Homo sapien(say-pee-en) - this is the binomial
name for humans.
The shapes, groups and cell wall types as well as bacterial
size and which food(s) the bacteria use are important to help
tell one species of bacterium from another. The science of classifying
living things is called "Taxonomy" (tax-onoh-me), from the Greek
words taxis=order and nomos=law
Some
Dangerous Bacteria
| Binomial
Name |
Disease(s) |
Ian's
Pronunciation |
| Yersinia
pestis |
Bubonic
plague |
yer-sin-ea
pest-iss |
| Salmonellosis |
Salmonella
species |
sell-mon-ella |
| Bacillus
anthracis |
Anthrax |
baa-sill-us
anne-threy-sis |
| Coxiella
burnetii |
Q
Fever |
cocks-e-ella
bur-net-e-eye |
Some other places you can find bacteria are:
- Yoghurt
- Your
intestines
- Animal
droppings
- Dirt
Parents
Please Note:
The phonetic representations are meant as a guide to pronunciation
only. Sound out each group of letters slowly,
then faster and faster until they become a word.
Organism
(or-ga-nizz-em) Any living thing. A "Microorganism" is a very
small (micro-) organism.
