1. “Bad News Wrapped Up In Protein”
Viruses
“Bad News Wrapped Up In Protein”
E. Christenbury

2. When did we first learn about viruses?
First known in the early 1800’s
1935: Tobacco Mosaic Virus -first seen under electron microscope

3. Viral Structure All viruses are composed of 2 basic parts:
Genetic material, either DNA or RNA
A protein coat that protects the virus
Envelope- outer layer over protein coat that helps to disguise the virus

4. Are Viruses Living? (What do you think?)
Are they cells?
Do they use energy to grow?
Do they use energy to respond to their surroundings?
Are they autotrophs or heterotrophs?
Do they give off waste?

5. So are they living?
No!

6. Who is hosting? Viruses need a host to multiply
Host- an organism that provides energy
Examples: people, birds, raccoon, tomato, potatoes
Viruses can multiply ONLY when they are inside a living cell
Does this make them
parasites?

7. Counterfeit Parasites
Parasites: an organism living on or in a host cell that causes harm to the host
Why are viruses counterfeits?
Though they cause harm, and destroy the host cell, viruses are not organisms because they are not living being.

8. Bacteriophages
Viruses that infect bacteria are known as bacteriophages 

9. Virus Overview
Viral diseases are among the most widespread illnesses in humans
These illnesses range from mild fevers to some forms of cancer and include several other sever and fatal diseases.
Transmission of these illnesses varies:
Human contact (shaking hands, kissing, sneezing)
Contaminated objects
Through soil, food, or water
Insect bites
Animal bites

10. Tobacco Mosaic Virus

11. Polio Virus

12. Yellow Fever
Stage 1 (infection): Headache, muscle and joint aches, fever, flushing, loss of appetite, vomiting, and jaundice are common. Symptoms often go away briefly after about 3-4 days. 
Stage 2 (remission):  Fever and other symptoms go away. Most people will recover at this stage, but others may get worse within 24 hours.
Stage 3 (intoxication): Problems with many organs occur. This may include heart, liver, and kidney failure, bleeding disorders, seizures, coma, and delirium.

13. Smallpox
A massive program by the World Health Organization (WHO) wiped out all known smallpox viruses from the world in the 1970s, except for a few samples saved for government research. Researchers continue to debate whether or not to kill the last remaining samples of the virus, or to preserve it in case there may be some future reason to study it.

14. Ebola virus

15. Viral Replication Virus attaches to the host cell
Virus attaches to the host cell
Virus injects genetic material
Viral DNA or RNA control production of viral protein and DNA or RNA
Protein and genetic material are assembled
Host cell bursts and virus is released

16. Why do we get infected with some viruses but not others?
Each virus is specific for the type of cell (respiratory, intestinal, bacterial) that they invade
This is because the receptor sites on the virus must match up with the receptor site on the host cell (embedded in the plasma membrane)
This “matching up” of receptor sites is the “lock and key” we saw in the video and on page 443 in your book
Example: Rhinovirus (cold virus) will only
infect respiratory tissue
Don’t need to know receptor sites, just mention immune system

17. Lytic Cycle- Called “Active Virus” in your book
Viruses attack quickly and recruit the host cell’s enzymes to make new viral parts for more virus particles.
Once assembled, the viruses will break free from the host (lysis) which kills the host or pinching out from the cell membrane (budding)
Not really

18. Lysogenic Cycle- Called “Hidden Virus” in your book
The virus injects its genetic instructions into the host’s genetic instructions. The virus remains “dormant” while the host cell undergoes cell reproduction.
Some environmental or predetermined signal “stirs” the provirus to enter into the lytic cycle.
Example: Hepatitis C, Herpes, Shingles
Not really, just give examples

19. How do viruses affect plants?
In plants they do the same thing, but can also cause changes in color (such as stripes in tulips)
-Much more difficult to get into cells because of cell wall

21. Eukaryotic Animal Cell

22. What works against viruses?
Vaccine (vak SEEN): usually consists of pathogens that have been weakened or killed but can still trigger the immune system to go into action
Vaccination or immunizations:
By pre-infecting the body with small
amounts of a particular virus, our body can build up antibodies that will fight the virus and give you immunity
* Antibiotics DO NOT work against viruses because they attack cell walls (which viruses do not have)

23. HIV (Human Immunodeficiency Virus)
HIV is a retrovirus which means that an enzyme called reverse transcriptase must convert the RNA into DNA before it can infect the cell.
6:00-7:50

24. HIV was first discovered in 1981 although they believe that the “crossover” from monkeys to humans probably occurred in the late 1950’s.
HIV has killed 28+ million people worldwide
Three million people died of AIDS in the year 2002 (that is the population of Chicago!)
HIV is NOT transmitted by saliva, sweat or tears or insects

25. Web citation http://www.howstuffworks.com/virushuman.htm