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CHAPTER SEVEN
“BACTERIA & VIRUSES”
p. 160
CHAPTER SEVEN “I CANS”
BACTERIA AND VIRUSES
1. I can explain the different ways to protect our food
from bacteria.
2. I can discuss the reasons why bacteria are
helpful and harmful.
3. I can list examples of bacterial diseases and how
they can be treated.
4. I can identify the steps of virus reproduction.
5. I can explain how vaccinations prevent disease.
• are unicellular.
• are prokaryotic.
- their DNA ‘floats around’
in the cytoplasm.
• creates foods.
- cheeses/yogurt.
• some cause disease.
ex. strep throat / anthrax
• have cell walls.
• live everywhere.
– in cold, hot, air, soil,
etc.
Two Kingdoms of Bacteria
1) Eubacteria
Phylum Bacteria
Phylum
Cyanobacteria
- can make their
own food.
2) Archebacteria
- oldest.
- live in extreme
conditions.
(page 191)
Bacteria was discovered by
van Leeuwenhoek in 1684.
There are three shapes of bacteria
(p. 187)
1) cocci
- round
2) bacilli
-rod shaped
3) spirilla
- spiral shaped
Some live by
themselves, in
chains, or in
groups called
colonies.
Bacteria can reproduce
asexually by quickly
splitting into two cells.
- called fission.
(20 minutes)
Bacteria colonies
They can also reproduce sexually
• called conjugation.
- an exchange of genetic
materials.
Bacteria Reproduction
Bacteria Structure
No nucleus.
Flagella for movement.
Draw and
label the
structures of
bacteria
- the outermost layer is the capsule.
- for protection.
- some create an endospore (or wall).
- it protects against high
temperatures.
Bacteria decays our food.
To prevent decay:
1) Dehydration
- water is removed
from food.
-bacteria need water
to survive.
2) High temperatures
- cook / boil / bake
- kills bacteria
3) Cold temperatures
- freeze /
refrigeration.
- stops or slows
bacteria growth.
4) Canning
- boiling
- then air-tight covering
5) irradiation
- exposing food to
radiation to kill
bacteria.
6) Pasteurization
- heating to 1500 then
quick cooled to 450.
- stored at low temps.
Ex. milk / apple juice
7) Seal it
- bacteria
cannot get
in.
Bacteria are very “tough”.
Can live in:
- hot springs
3500 F
- ice
- ocean depths
- in your intestines
- without oxygen
- anaerobic
ASSIGNMENT:
BOOK QUESTIONS
PAGE 191: 1 / 2 / 4
PAGE 199: 3 / 4
Some Bacteria can cause disease:
ex. pneumonia / anthrax
Pathogen
- any organism which
causes disease.
Some bacteria destroy
cells by releasing a
toxin.
ex. botulism
‘flesh-eating’ bacteria
Antibiotics
(against life)
- used to kill or slow
the growth of
bacteria.
Ex. penicillin
amoxocillin
What is antibiotic
resistance?
Cyanobacteria
- second phylum of
Eubacteria.
- have chlorophyll but not
chloroplasts.
- also called “blue-green
algae”.
- many live in long
chains.
- not all are blue-green:
there are red, yellow,
and black.
(p. 190)
There are different pigments which give
cyanobacteria their color.
They are a source
of food for
other organisms.
They are the cause of the ‘green slime’ on the
surface of ponds.
Cyanobacteria are called nitrogen-fixers.
- they grow among the
roots of certain plants.
Ex. soybeans, alfalfa
- take nitrogen out of the
air and create nodules
in the soil.
- adds nutrients.
- saves $$ on fertilizer.
Soybean ‘nodules’
A lot of nutrients in the water causes rapid
growth called a ‘bloom’.
- the cyanobacteria
die and sink to
the bottom.
- other bacteria
decompose them.
- it takes oxygen
out of the water.
- the fish die…
ASSIGNMENT:
WORKSHEET
“BACTERIA”
HELPFUL BACTERIA
1) Keeps the
environment free of
dead material.
- decays plants and
animals.
-breaks down our
sewage and garbage.
-returns nutrients to
the soil.
Saprophyte
- any organism
which uses dead
material for food.
2) Found in our
intestines.
- helps break
down our food.
3) Nitrogen fixers
- put nutrients back
into the soil.
4) Economically important.
- cheese, and yogurt are made from milk
‘soured’ by bacteria.
- different bacteria make a different type
of cheese.
5) Can make medicines.
• Can make vaccines to
prevent some bacterial
diseases.
• Ex. tetanus
Harmful Bacteria
1) Can cause fatal
diseases.
ex. Pneumonia,
anthrax.
2) Can spoil food
- could lead to
starvation.
ASSIGNMENT:
WORKSHEET
‘BACTERIA IN YOUR LIFE’
VIRUSES
( p. 52 - 55 )
• are not cells
- there is not a
nucleus, cytoplasm,
etc.
• spread disease.
• very small microscopic.
• many different
shapes. (p. 52)
Viruses are not
considered to be alive.
- are not in any
kingdom.
- cannot respond to
stimuli.
- can reproduce only
inside a living cell.
A VIRUS IS MADE UP OF
TWO PARTS:
cccc
1) Protein coat
- the outside.
- for protection
2) Nucleic Acid
- genetic material.
VIRUSES
HOW DO THEY CAUSE DISEASE?
1) Attach
-the virus attaches
itself to a host cell
of an organism.
2) Invade
- the virus injects its
nucleic acid into the
host cell
3) Copy
- the virus’ nucleic
acid “takes-over”
the host cell.
- it forces the cell to
make copies of the
virus instead of new
cells.
4) Release
- the cell finally
bursts. Hundreds of
new viruses are
released to ‘attack’
new cells.
Chicken pox, AIDS,
the common cold,
measles, and small
pox are all caused
by viruses.
- spread by water,
touch, air, and
insects.
ASSIGNMENT:
WORKSHEET
“VIRUS ATTACK”
Latent viruses
- may “hide” in the
host cell for years
before “taking
over”.
ex. cold sore
HIV
Active viruses enter
and take over a cell
immediately.
ex. common cold
VACCINES
• made of a weakened or
damaged virus that
cannot cause the
disease.
• cannot cure viral
diseases
- it prevents them
from happening.
First created by Edward Jenner in 1796
to fight smallpox.
He noticed the
milkmaids did not
have the scars from
smallpox.
All had clear skin but
did have cowpox
before.
He used the ‘sores’
from cowpox
- the body reacts and destroys the
‘weak’ virus.
-the body produces an antigen which
“remembers” the virus and will destroy it
when enters the body again.
Vaccinations have almost eradicated
many diseases.
Example: Polio
- attacks the
nervous system.
President Franklin
Roosevelt (FDR)
Example II:
Smallpox
- thought to be
eradicated in
1981.
VACCINES
The body does have natural defenses
against viruses.
Interferon
- a chemical which
slows down the
reproduction of
viruses.
- now used in cancer
treatments.
Vaccines can prevent epidemics.
- the rapid spread of
a disease through
an area.
Ex. influenza (1917
- 1919)
-killed 10 million
world wide.
“Black Death” or
Bubonic Plague.
- 1300’s in Europe.
Viruses can change or mutate.
- there are thousands
of types of the
common cold.
- Scientists are now
worried about “bird
flu”
- mutating into a
human disease.
ASSIGNMENT:
WORKSHEET
“VIRUSES”
Viruses may someday help :
Ex. Gene therapy
- a gene is ‘defective’.
ex.sickle-cell anemia
- a virus’ nucleic acid
will be replaced with
‘healthy’ DNA.
- the virus attacks and
May help people with
replaces the ‘bad’
genetic diseases.
DNA
ASSIGNMENT:
Using Vocab.
P. 204 1 - 7
Checking Concepts
P. 204 9 - 15
Skip #12
CHAPTER SEVEN “I CANS”
BACTERIA AND VIRUSES
1. I can explain the different ways to protect our food
from bacteria.
2. I can discuss the reasons why bacteria are
helpful and harmful.
3. I can list examples of bacterial diseases and how
they can be treated.
4. I can identify the steps of virus reproduction.
5. I can explain how vaccinations prevent disease.