WHAT DO YOU THINK IS THE SMALLEST ORGANISM
ON EARTH? WHERE DOES IT LIVE?
Take 5 minutes to answer this in your
notebook.
BACTERIA !!!
Bacterial cells are very small - about 10
times smaller than most plant and animal cells.
THERE'RE MORE BACTERIA IN YOUR MOUTH
THAN THERE ARE PEOPLE IN THE WORLD.
A DOG’S MOUTH HAS FEWER GERMS THAT A
HUMAN’S MOUTH!
THE AVERAGE OFFICE DESK HAS 400
TIMES MORE BACTERIA THAN A TOILET.
MOBILE PHONES HAVE 18 TIMES
MORE BACTERIA THAN TOILET HANDLES.
WHAT DO YOU ALREADY KNOW?
• What are the characteristics of bacteria?
• What do they eat?
• Are they living? Why or why not?
WHAT DO YOU ALREADY KNOW?
• Are all bacteria harmful?
• Are some bacteria good?
• What’s the best and easiest thing to
do to avoid getting sick?
BACTERIA
• Bacteria are prokaryotic, unicellular
organisms.
• Bacteria have the greatest percentage of the
biomass on Earth!
BACTERIOLOGY: THE STUDY OF BACTERIA
WHAT DO BACTERIA LOOK LIKE?
spherical
(coccus)
rod-shaped
(bacillus)
spiral
(spirillum)
BACTERIA ARE
Bacteria have ALL the characteristics of living
things.
•Growth
•Reproduction
•Movement
•Need to eat food
HOW DO BACTERIA REPRODUCE?
• Bacteria grow in number, not in size.
• Bacteria reproduce through asexual
reproduction
• Humans grow in size from child to adult
(sexual reproduction)
Hands On: Real World Lessons for Middle School Classrooms©
University of Tennessee, Knoxville 2009
HOW DO BACTERIA REPRODUCE?
• Make copies of themselves by dividing in half
• Genetic information in the parent cell is passed to
each new daughter cell
• The two cells will now be identical
Hands On: Real World Lessons for Middle School Classrooms©
University of Tennessee, Knoxville 2009
HOW DO BACTERIA EAT?
• Some make their own food from
sunlight—like plants
Photosynthetic
bacteria
• Some are scavengers
• They eat the environment around them
• Example: The bacteria in your stomach are now
eating what you ate for breakfast
• Some are warriors (pathogens)
Harmless bacteria
on the stomach
lining
• They attack other living things
• Example: The bacteria on your face can attack skin
causing infection and acne
Hands On: Real World Lessons for Middle School Classrooms©
University of Tennessee, Knoxville 2009
E. Coli O157:H7
is a pathogen
HOW DO BACTERIA GET THEIR FOOD?
• Bacteria can eat dead organisms or organic waste (fruits
and veggies)
• Or they can live on or inside of living organisms (humans),
eating from the organism
VOCABULARY
• HETEROTROPHS: an organism that
relies on other sources for its nutrition.
• AUTOTROPHS: an organism that makes
its own food, usually by
photosynthesis.
WHERE DO BACTERIA LIVE?
• Bacteria live on every habitat on Earth.
• Bacteria live IN and ON almost every organism, living or
dead!!
• Hundreds of species of bacteria live on your skin RIGHT
NOW.
COMPREHENSION CHECK
What is an autotroph?
COMPREHENSION CHECK
What are the characteristics of
living things?
COMPREHENSION CHECK
How is bacterial reproduction
different from animal
reproduction?
NATURE’S ULTIMATE SURVIVORS
• Extremophiles are bacteria that
THRIVE in extreme habitats. They have
different names depending on the
habitat they live in.
Discovered in the 1970s
in hot springs in Yellowstone
National Park (right) and
hydrothermal vents on the
ocean floor.
Grand Prismatic Spring in
Yellowstone National Park.
Some of the coloring is
caused by extremophiles!
TEMPERATURE
EXTREMES:
• Thrive in high-temperature environments.
• Environments such as thermal vents, volcanoes and hot
springs
They can withstand
water temperatures
over 200 deg
Fahrenheit and
require a temperature
over 194 degrees
Fahrenheit to
survive!
A sulfide-rich "black
smoker" vents hot water
into the cold ocean.
Microbial extremophiles
live in the vented
materials.
How do they live in such a harsh
environment?
• They have special enzymes (proteins) that
are heat stable and help them withstand
high temperatures without melting.
• Thrive in extremely
cold environments
• Example: The arctic
and Antarctic tundras
• 1/2 of Earth’s surface
is oceans between 10C
& 40C
• Deep sea –10C to 40C
How do they survive in such harsh
environments?
• Most of them use
photosynthesis
• Their cell membrane has lots of
fats that help them survive in the
cold
• The word halophile means “salt loving”.
• A halophile thrives in extremely salty (NaCl
concentrated) environments.
Their habitats include
super salty lakes (the
Great Salt Lake and the
Dead Sea), salt marshes,
and even salted meats.
WHAT IS A HALOPHILE?
Some extreme
halophiles can live in
solutions of 35% salt.
This is extreme
compared to regular
seawater, which is
only 3% salt.
They have a special
cell wall that controls
the movement of
salts into the cell.
The Dead Sea: 34% Salt
UNUSUAL HABITATS
• Bacillus (a type of
halophile) was found
in the nasal cavities
of desert iguanas.
• Thrive in highly acidic
environments
• These environments
usually have a pH level
below 5.
• They have specialized
cells that regulate their
pH level.
WHERE CAN YOU FIND ACIDOPHILES?
• Thermal vents
and some hot
springs
• Extremely acidic
bacteria are found
in the runoff of
mine drainage
where the pH is
below 1, more
acidic than
stomach acid.
Thrive in radioactive environments
• Environments
include: Chernobyl,
inside of nuclear
power plants
• Radiophiles can survive
very high levels of
radiation: over 1,000 times
greater than a human cell
can withstand.
• They can repair genetic
mutations caused by
radiation very quickly
because they have many
DNA-repairing enzymes!
REVIEW
You should be able to….
• Describe extremophiles and name the types
• Know the characteristics of living things
• Name the three bacterial shapes
• Describe how bacteria reproduce
• What is the study of bacteria called?
• Name 3 ways bacteria eat
• Know the difference between autotrophs &
heterotrophs
EXTREMOPHILES 101 VIDEO
• https://www.youtube.com/w
atch?v=MY1d5Saqrc4
WHAT DO YOU THINK GOOD BACTERIA DO?
TAKE 5 MINUTES TO ANSWER THIS IN YOUR NOTEBOOK.
ARE ALL BACTERIA BAD?
• No, most are harmless
• Some are even helpful
• Pathogens are
organisms that cause
disease or illness in
their host. Pathogens
are commonly called
GERMS.
Hands On: Real World Lessons for Middle School Classrooms©
University of Tennessee, Knoxville 2009
ARE ALL BACTERIA BAD?
There are 2 main ways
that bacteria help us
that you should know….
Hands On: Real World Lessons for Middle School Classrooms©
University of Tennessee, Knoxville 2009
BACTERIA HELPS US MAKE NEW FOODS
• Lactobacillus: Turns milk into cheese, yogurt and
produces vitamins in your intestine
• Leuconostoc: makes pickles & sauerkraut
• Pediococcus: makes pepperoni, salami, & summer
sausage
Bacteria make yogurt, cheese
& pickles through the process
of lactic acid fermentation
BACTERIA HELP US DIGEST THE FOOD WE EAT
• If it weren’t for the
help of bacteria
living in your gut,
there are many
things that you
wouldn’t be able to
digest at all.
HOW MUCH BACTERIA DO YOU HAVE IN YOUR
BODY?
• Your intestines alone are home to 100 trillion
bacterial cells!
• Altogether, these microbes may weigh as much as
2–5 pounds (1–2 kg), which is roughly the weight
of your brain.
The relationship between
you and your bacteria is an
example of symbiosis: a
relationship between two
different organisms that
live closely together.
Your bacteria receive a safe home and plenty
to eat, and in return they help you break down
food to get the nutrients that you need to
survive and grow.
The good bacteria in our bodies are
part of….
THE GUT MICROBIOME:
The total number of bacteria,
viruses, and even fungi
present in the
gastrointestinal tract.
• Bacteriotherapy is the purposeful use of
bacteria or their products in treating an
illness.
Can you think of an example?
BACTERIOTHERAPY
• A fecal transplant is when a doctor transplants feces from
a healthy donor into another person to restore the balance
of good bacteria in their gut (yes, really!!!)
• Fecal transplants may help treat gastrointestinal infections
caused by an unbalanced microbiome. It allows the
recipient’s body to grow good bacteria.
COMPREHENSION CHECK
What is the gut microbiome?
COMPREHENSION CHECK
What is an example of bacteriotherapy?
COMPREHENSION CHECK
Who would need bacteriotherapy?
COMPREHENSION CHECK
What are 2 ways bacteria can be helpful?
YOU AND YOUR BACTERIA
• https://www.youtube.com/watch?time
_continue=19&v=1X8p0vhsWRE
INFECTIOUS AGENTS
WHAT IS A VIRUS?
Virus: A virus is an infectious agent made up of
genetic material (DNA or RNA) and wrapped in a
protein coat called a capsid.
Virology: the study of viruses.
VIRAL SHAPES
ARE VIRUSES LIVING
THINGS?
So what DO viruses do??
https://www.youtube.com/watch?v=YS7vsBgWszI
VIDEO CLIP:
How Viruses
Work
TO REVIEW....
 What are the differences between viruses and bacteria?
 Are all bacteria harmful? Explain.
 When you get a cold, should you take an antibiotic to help you get better?
Why?
 What’s the best and easiest thing to do to avoid getting sick?
Bacteria
Virus
Both