Transcript Bacteria

Bacteria
The Good
The Bad
And…
The Ugly!
Bacteria
Microscopic and single-celled
Living and contains DNA
Mostly prokaryotic: no nucleus
Live on earth- in soil, air, water, plants,
animals and people.
Group together in colonies (clusters or
chains)
Some help humans digest food and
protect against harmful bacteria.
DID YOU KNOW?
Seconds after you were born, tiny
organisms surrounded and invaded your
body.
Millions of these organisms coat your skin.
As you sit in your desk listening to this
presentation, they swarm inside your
nose, throat, and mouth.
There are more of these organisms living
in your mouth than there are people who
are living on Earth.
The human body has more bacteria
than it has cells. An unborn baby
is completely free of bacteria, but
the instant they are born they
acquire billions of bacteria.
Bacteria are essential for a
healthy body.
www.pregnancy-leads-to-new-babies.com/ images/
There are more than 10,000 kinds of bacteria and an
unknown number still waiting to be discovered.
www.elements-of-design.net/
BACTERIA INFORMATION
Bacteria are classified into three
groups according to their shape:
round (cocci ), spiral (spirilla ),
and rod (bacilli ) shape.
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Some round shape bacteria can cause infections in
people.
Some spiral shape bacteria are used to make cheese.
Some rod shaped bacteria have been known to cause
food poisoning.
aquat1.ifas.ufl.edu/ guide/bacecoli.jpg
www.redcolony.com/ pics/content/bacteria.jpg
io.uwinnipeg.ca/.../ 27-03c-HelicalProkaryote.jpg
Bacteria are so small that about 1,000 could fit on the
head of a pin.
www.agen.ufl.edu
Bacteria Multiplication
Sexual reproduction
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Two parents
Conjugation (transfer of genetic material
through bridge)
Asexual reproduction
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Binary Fission - Simply splitting in two
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Let’s watch it!
More on Growth
Rapid reproduction, as
fast as once every 20
minutes
Continues until they run
out of the basics
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Food
Air
Space
Thrive in warm, damp
places (e.g. human body,
uncovered food)
SURVIVAL NEEDS
Food
Water
Air
Waste Disposal
Temperature of Environment
Reproduction
SURVIVAL NEEDS
Obtaining food
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Autotrophs-Make their own food
Some make food by capturing and using the sun’s
energy as plants do.
Some use energy from chemical substances in
their environment to make food.
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Heterotrophs-Obtain food by consuming
autotrophs or other heterotrophs
Heterotrophic bacteria may consume a variety of
foods- from milk and meat to decaying leaves on a
forest floor.
SURVIVAL NEEDS CONTINUED
Respiration-bacteria need a constant
supply of energy to carry out their
functions. This energy comes from food.
The process of breaking down food to
release its energy is call respiration.
MOVEMENT
The typical bacterial cell has a flagellum (plural
is flagella.) They may have many, one, or none.
A flagellum is a long, whip like structure that
extends from the cell wall and helps the
bacterium move by spinning like a propeller.
Most bacteria that do not have flagella cannot
move on their own. Instead they depend on air,
water currents, clothing, and other objects to
carry them from one place to another.
The Good:
HELPFUL BACTERIA
How?
~95% don’t hurt
you!
HELPFUL BACTERIA
Human Body
 Helps our digestive system and helps fight off bad bacteria
FOOD
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Cheese, yogurt, apple cider, sour cream
Environmental recycling
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Bacteria that lives in the soil are decomposers
Organisms that break down large chemicals in dead organisms into small
chemicals.
Decomposer- an organism, often a bacterium or fungus, that feeds on and
breaks down dead plant or animal matter. (vocabulary section)
Environmental Cleanup
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Some bacteria are used to convert the dangerous chemicals in an oil
spill into harmless substances.
The Bad:
Diseases Caused by Bacteria
Strep Throat
Plague
Tooth Decay
Tetanus
E coli
Anthrax
Health and Medicine and prevention
Washing your hands, washing and protecting open wounds, and
staying healthy by exercising are, ways to prevent bacteria from
entering your body.
Vaccines are a weakened form of the disease that are injected into
a person. The person’s body then makes antibodies to prevent the
actual disease.
PREVENTING HARMFUL BACTERIA
IN FOODS
Food manufacturers use a variety of methods to
prevent harmful microbes from infecting foods.
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Heating or cooling will affect the number of bacteria
that can grow in it.
Boiling liquids at high temperatures destroys microbes.
Freezing food makes it too cold for microbes to grow quickly.
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Six ways to control the growth of bacteria in foods
are:
Pasteurization
Drying
Refrigeration
Freezing
Dehydration
Vacuum-pack
Pasteurization is a heating process to kill bacteria in foods.
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Canning first destroys bacteria through heating and then
the food is placed in a sterilized container and sealed.
Drying removes water from the food that bacteria need to
grow and reproduce.
Freezing slows down the spoilage process by changing
water into ice; a form that the bacteria cannot use.
Pasteurization destroys most of the existing spoilage
organisms by heating the food to a high temperature for a
short duration.
Pickling or fermentation (culturing) leaves the food with a
higher level of acid, making it an inhospitable environment
for spoilage bacteria.
UHT (ultra-high temperature) uses heat higher than
pasteurization: then pressure is applied resulting in a sterile
product.
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Vacuum packaging uses a vacuum sealed, abrasionresistant moisture-impermeable film that inhibits molds,
yeasts, and bacterial growth on the surface of the things
such as meat. Since there is no air in the package, vacuumpackaged meat will have a darker, purple color before
being opened. Once the meat is exposed to oxygen, it will
turn the familiar bright red color, because of the natural
reactions within the package. Fresh vacuum-packaged meat
will give off a slight odor when opened. The smell will
dissipate within a few minutes. This should not be confused
with spoilage.
Smoking adds smoke-born chemicals to food that help
destroy potential spoilage organisms.
Chemical additives are designed to destroy spoilage
organisms or inhibit their growth. Sugar and salt are
examples of additives that have been in use for centuries.
Both of these work by drawing water out of the spoilage
organisms, thus preventing their growth.
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Irradiation is a process that pasteurizes food by using
energy, just like milk is pasteurized using heat. Irradiation
DOES NOT make food radioactive. The food never
touches a radioactive substance. Irradiation destroys
insects, fungi, and bacteria. Fewer nutrients are lost during
irradiation than in cooking and freezing. Food irradiation
has been approved in 37 countries for more than 40
products. Astronauts have eaten irradiated foods for years.
Food additives are any substances added to food. Sugar,
salt, and corn syrup are the most commonly used food
additives. Food additives keep foods fresh, slow microbial
growth, give desired texture and appearance, and aid in
processing and preparation.