Viruses and Bacteria
Table of Contents
Viruses
Bacteria
Viruses, Bacteria, and Your Health
Viruses and Bacteria - Viruses
Deadly Virus
USAMRID
Click the Video button to watch a movie
about deadly viruses.
Viruses and Bacteria
Characteristics of Living Things
Made of Cells
Use Energy
Similar Chemistry
Respond
Grow
Reproduce
Viruses and Bacteria - Viruses
What Is a Virus?
www.cellsalive.com/howbig.htm
-A virus is a nonliving particle
that enters and then
reproduces inside a living cell.
-Virus particles are very tiny.
Viruses and Bacteria - Viruses
The Structure of Viruses
-All viruses have two basic parts:
1. protein coat--that protects the virus
2. inner core--made of DNA or RNA. (Some viruses
are surrounded by an outer membrane envelope.)
Viruses and Bacteria
The Shape of Viruses
Viruses come in many shapes:
Many-sided (Icosahedron)
Example: Polio virus
Helical rods
Example: Tobacco mosaic virus
Robotlike
Example: Bacteriophage
Spherical or round
Example: HIV
Viruses and Bacteria
Why are Viruses Nonliving
-Nonliving characteristics of viruses:
1. are not made of cells
2. do not use their own energy
3. do not grow or respond
4. can not make food, take in food or produce
wastes.
-Living characteristics of viruses:
1. contain DNA or RNA
2. contain proteins
3. can multiply---but NOT on their own
Viruses and Bacteria
What cells do viruses enter?
-Viruses can enter the cells
of ANY living organism.
-There are viruses that infect
plants, animals, fungi,
protists and even tiny
bacteria cells!!!!
-They cause disease and
are known as pathogens
(any disease-causing agent).
Viruses and Bacteria - Viruses
Active and Hidden Viruses Activity
Click the Active Art button to open a browser window and
access Active Art about active and hidden viruses.
Viruses and Bacteria - Viruses
How Viruses Multiply
Active viruses enter cells immediately and begin to multiply,
leading to the quick death of the invaded cells. The steps are:
Attach
Release
Inject
Assemble
Copy
Viruses and Bacteria - Viruses
How Viruses Multiply
Hidden (Latent) viruses “hide” for a while inside host cells
before becoming active.
Attach
Release
Inject
Hide
Assemble
Copy
Viruses and Bacteria - Viruses
Sequencing
As you read, make two flowcharts that show how active and
hidden viruses multiply. Put the steps in the process in
separate boxes in the flowchart, in the order in which they
occur.
How Active Viruses Multiply
Attach: Virus attaches to the surface of a living cell.
Inject: Virus injects genetic material into cell.
Copy: Cell makes copies of viral proteins and genetic material.
Assemble: Viruses assemble.
Release: Cell bursts, releasing viruses.
Viruses and Bacteria - Viruses
Sequencing
As you read, make two flowcharts that show how active and
hidden viruses multiply. Put the steps in the process in
separate boxes in the flowchart, in the order in which they
occur.
How Hidden Viruses Multiply
Attach: Virus attaches to cell.
Inject: Virus injects its genetic material.
Hide: Virus’s genetic material becomes part of cell’s genetic material.
Copy: Cell makes copies viral proteins and genetic material.
Assemble: Viruses are assembled.
Release: Cell bursts, releasing viruses.
Viruses and Bacteria
Common Viral Diseases
DNA Viruses
Chicken pox
Small pox
Herpes
Parvovirus
Bacteriophages
Hepatitis B
Review Characteristics
Of Viruses
RNA Viruses
Measles
Mumps
Rubella
Polio
AIDS
Colds
Flu
Ebola
Hepatitis A C and E
Viral pneumonia
Viruses and Bacteria
Review the steps of an active virus infection by completing
the following activity.
Virus Infection Review
Flipchart Activity
Viruses and Bacteria
How Do You Catch a Virus?
1. Contact with an infected person —coughing,
sneezing, shaking hands, etc. (colds and flu)
2. Contact with a contaminated object —sharing
a drinking cup or utensils, etc. (colds and flu)
3. Insect and animal bites (West Nile and rabies)
4. Contaminated food and water (Rotavirus)
5. Sexual contact and exchange of body fluids
(AIDS)
Viruses and Bacteria
Fighting Viruses
-The Immune System is the body’s only defense
against viruses.
-Three types of white blood cells and specific
antibodies are involved.
-There mission:
RECOGNIZE
DESTROY REMEMBER
-Antibiotics and medicines do not work against
viruses. Medications only treat symptoms. They
can not cure a viral infection.
Viruses and Bacteria
Vaccinations
-Vaccines—made from weakened or damaged virus
particles that can no longer cause infection.
1. Trigger the body’s immune system to prevent
infections: not cure them.
2. First vaccine was developed by Dr. Edward Jenner
in 1790 to prevent small pox.
3. Are now used to prevent many viral diseases.
Show video then notes
Viruses and Bacteria
Gene Therapy
-Gene Therapy is a new technique in which scientists
hope to cure people of genetic diseases using viruses.
*Replace a virus’s DNA with information needed to
repair a person’s defective genes.
*The virus infects the cell with the good information.
*Good genes replace bad genes and the person is
cured.
*Only animal studies have been done so far.
*May someday cure diseases like cystic fibrosis.
Viruses and Bacteria
HIV and AIDS
AIDS—acquired immune deficiency syndrome
First known case: Africa 1959.
HIV—human immunodeficiency virus
-The Virus that causes AIDS
-First seen in 1978: Identified and named in 1983
-Attacks the cells of the immune system so the
body cannot fight infections.
-It can take up to 10 yrs for an HIV infected
person to develop full-blown AIDS.
-RNA virus, so it mutates rapidly
-Work has begun on a vaccine: has not
been successful.
Viruses and Bacteria
The Spread of Viruses
-World-wide the spread of viruses is increasing rapidly.
-Why are previously rare viruses, like ebola, being
reported in new countries?
1. Global travel and trade
2. World wide population growth.
3. Humans exploring remote areas.
Viruses and Bacteria
End of Section:
Viruses
Viruses and Bacteria - Bacteria
The Bacterial Cell
-Bacteria are prokaryotes.
*They have no nucleus.
*Their DNA floats free
in a gel-like substance
known as cytoplasm.
*Surrounded by a cell
membrane and cell wall.
*Some move using taillike structures known as
flagella. (one or many)
*Ribosomes also float in
the cytoplasm. They
make proteins.
Viruses and Bacteria
Shapes of Bacteria
Three basic shapes:
1. Bacilli—rod-shaped
3. Spirilla—spiral-shaped
2. Cocci—sphere-shaped
Viruses and Bacteria
Obtaining Food and Energy
-Some bacteria are autotrophs (make their own food).
1. Photoautotrophs—use sunlight to make food
Example: Cyanobacteria (blue-green bacteria)--all
contain chlorophyll and are found in
lakes and ponds (usually as a cloudy
scum). Some have other pigments
that make them red, yellow or black.
(Red Sea named for red cyanobacteria).
2. Chemoautotrophs—use the energy from chemicals in their
environment to make their food. They live deep in
the mud or in extreme environments like hot springs.
Viruses and Bacteria
Obtaining Food and Energy
-Other bacteria are heterotrophs (cannot make food).
*They feed on many different things.
*Some are important saprophytes—feeding on
decaying organisms.
Viruses and Bacteria
Reproduction
-Most bacteria reproduce by binary fission.
*Binary fission is a type of asexual reproduction
where one cell divides into two identical cells.
*Some bacteria can double their population every
20 minutes if conditions are just right. This means
that one cell can become one billion in just 10 hrs.
Viruses and Bacteria
Sexual Reproduction
-Some bacteria use a simple
form of sexual reproduction
known as conjugation.
*Conjugation does not
increase the number of
bacteria cells. It just creates
new combinations of
genetic material to be
passed on when new cells
form through fission.
Viruses and Bacteria - Bacteria
More on Bacteria
Click the PHSchool.com button
for an activity about bacteria.
Viruses and Bacteria - Bacteria
Population Explosion
Suppose a bacterium
reproduces by binary fission
every 20 minutes. The new cells
survive and reproduce at the
same rate. This graph shows
how the bacterial population
would grow from a single
bacterium.
Viruses and Bacteria - Bacteria
Population Explosion
Reading Graphs:
What variable is being
plotted on the horizontal
axis? What is being
plotted on the vertical
axis?
Horizontal axis–time
(minutes); vertical axis–
number of bacterial cells.
Viruses and Bacteria - Bacteria
Population Explosion
Interpreting Data:
According to the graph,
how many cells are there
after 20 minutes? One
hour? Two hours?
2 cells after 20 minutes;
8 cells after one hour;
64 cells after two hours.
Viruses and Bacteria - Bacteria
Population Explosion
Drawing Conclusions:
Describe the pattern you
see in the way the
bacterial population
increases over two hours.
The number of cells doubles
with each division.
Viruses and Bacteria - Bacteria
Population Explosion
Predicting:
Do you think the bacterial
population will continue to
grow at the same rate?
Why or why not?
Not likely. The bacteria will
continue to reproduce at this
rate only as long as the
conditions are favorable.
Viruses and Bacteria
Role of Bacteria in Nature
-Bacteria can be helpful, harmful, or harmless.
Helpful Bacteria:
*Produce oxygen in the air
*Used in food production
(yogurt, cheese, pickles,
sauerkraut, sour cream)
*Decomposed dead organisms
*Turn nitrogen gas into usable
nitrogen products for plants
(nitrogen-fixing bacteria)
*Clean up oil spills
*Help digest food and make
vitamins
*Make medicines
Harmful Bacteria:
*Spoil food
*Cause disease
(Examples: strep throat, botulism,
diptheria, tetanus, whooping cough,
TB, Lyme disease, and anthrax)
Harmless Bacteria:
*Live among us totally
undetected. Do not
hurt or help.
Viruses and Bacteria
Bacterial Diseases
Bacterial diseases are spread in the same manner as viral
diseases:
Contact with an infected person (TB and strep throat)
Contact with a contaminated object (strep throat and tetanus)
Insect and animal bites (Lyme disease)
Contaminated food and water (botulism)
Sexual contact and exchange of body fluids (Hepatitus C)
Viruses and Bacteria
Fighting Bacteria
-Antibiotics can be used to kill bacteria.
*Antibiotic resistance —some bacteria can survive in
the presence of antibiotics. They multiply and the
disease continues. This makes some diseases
difficult to treat.
-Preventing infections is important
*Vaccines can be used for both bacterial and
viral infections.
*Hand washing
*Don’t share cups and utensils
*Cook and store foods properly
*Eat healthy, get rest, drink fluids, & exercise
Viruses and Bacteria - Viruses, Bacteria, and Your Health
Antibiotic Resistance
Click the Video button to watch a movie
about antibiotic resistance.
Viruses and Bacteria
End of Section:
Bacteria
Viruses and Bacteria - Viruses, Bacteria, and Your Health
Common Bacterial Diseases
Many bacterial diseases can be cured with antibiotics.
Viruses and Bacteria - Viruses, Bacteria, and Your Health
Common Viral Diseases
Unlike with bacterial diseases, there are currently no
medications that can cure viral infections.
Viruses and Bacteria - Viruses, Bacteria, and Your Health
Using Prior Knowledge
Look at the section headings and visuals to see what this
section is about. Then write what you already know about
diseases caused by viruses and bacteria in a graphic
organizer like the one below. As you read, write what you
learn.
What You Know
1.
2.
You can catch a cold from somebody who has one.
Some diseases can be treated with medicines.
What You Learned
1.
2.
You can catch diseases through contact with an infected person, a
contaminated object, an infected animal, or an environmental source.
Antibiotic resistance results when some bacteria are able to survive in
the presence of an antibiotic.
Viruses and Bacteria - Viruses, Bacteria, and Your Health
Links on Infectious Diseases
Click the SciLinks button for links on infectious diseases.
Viruses and Bacteria
End of Section:
Viruses, Bacteria,
and Your Health
Viruses and Bacteria
Graphic Organizer
Nonliving
Can be
useful
Treated with
antibiotics
Viruses and Bacteria
End of Section:
Graphic Organizer