1. Wednesday Jan 29, 2014
Take out your note packet from last week and open to the “VIRUS” section.

2. Viruses Doesn’t belong to any kingdom -It’s not a plant or an animal.
-It’s not a fungi, protist, or bacteria.
WHAT IS A VIRUS?

3. How a VIRUS attacks your body
FLU ATTACK!!!

4. 1. A virus is an infectious agent made up of nucleic acid (DNA or RNA) wrapped in a protein coat called a capsid.
2. Viruses have no nucleus, no organelles, no cytoplasm or cell membrane—Non-cellular and Non-living
This is why it does NOT belong to any kingdom. vs

5. 3. Viruses are parasites —an organism that depends entirely upon another living organism (a host) for its existence in such a way that it harms that organism.
I hate fleas !!!
A flea is a parasite to a dog and is harmful to the dog.

6. Viruses have either DNA or RNA but NOT both
RETROVIRUS:
Has RNA instead of DNA
The genetic material mutates (changes) often
Example: HIV
HIV Infected Cell
(This is the reason why HIV is so incurable.)

7. Bacteriophage—viruses that infect bacteria
Capsid (protein coat)
inside contains either
RNA or DNA
2. Flu (influenza), HIV
DNA or RNA
Surface Marker
Capsid (protein coat)

8. Bacteriophage—a virus that infects bacteria (bacteria is the host)
Capsid
Nucleic Acid
Bacteriophage—a virus that infects bacteria (bacteria is the host)

9. C. Replication is how a virus spreads.
A virus CANNOT reproduce by itself—it must invade a host cell and take over the cell activities, eventually causing destruction of the cell and killing it.
(The virus enters a cell, makes copies of itself and causes the cell to burst releasing more viruses.
DNA/RNA is copied.
DNA/RNA injected into cell.
Virus attaches to cell.
Step 3
Step 2
Step 1
Virus copies itself.
Cell bursts (lyses) and releases new viruses.
Step 4
Step 5

10. Certain viruses can only attack certain cell types
Certain viruses can only attack certain cell types. They are said to be specific.
Example: The rabies virus only attacks brain or nervous cells.
Surface Markers
Receptor Sites
It’s like the pieces of a puzzle. The ends have to match up so only certain pieces fit.

11. A virus recognizes cells it can infect by matching its surface marker with a receptor site on a cell.
Virus
Surface Markers
Cell
Receptor Sites

12. The virus attaches to bacteria (host)
                       
The virus inserts its DNA into the bacteria
The virus takes over the cell's machinery
  “hijacking” the cell
The virus reproduces itself and self-assembles. 
                   
The host cell is destroyed

13. The virus binds to bacteria (host)
The virus inserts its DNA into the bacteria
The viral DNA gets incorporated into the cell’s chromosome
Viral DNA is replicated along with chromosomal material
NO disease shows up
*BUT if the host is STRESSED, the virus can change from the lysogenic to lytic cycle and make you SICK.

14. Lytic vs. Lysogenic

15. 2.Viruses can be beneficial:
F. Importance:
1. Viruses can be harmful or
pathogenic-causing disease
pathogen- disease producing agent
Human Diseases caused by viruses
i. Flu (Influenza) – fever, cough, sore throat
ii. HIV – weakens the immune system. The HIV virus causes AIDS
iii. Common cold and warts.
b. Viruses disrupt the body’s normal equilibrium/balance
c. Can be prevented with vaccines, but NOT treated with antibiotics.
(antibiotics treat bacteria)
2.Viruses can be beneficial:
Genetic Engineering—harmless virus carries good genes into cells.

17. Virus Living Cell RNA or DNA core (center), protein coat (capsid)
Cell membrane, cytoplasm, genetic material, organelles
Structure NO
Copies itself only inside host cell
Yes
Reproduction
DNA and RNA
Genetic Material
DNA or RNA
Growth and Development NO
YES—Multicellular Organisms
Obtain and Use Energy NO
YES
Response to Environment
YES NO
Change over time
YES
YES

18. Are viruses living? NO TWO
How many characteristics of life do viruses possess?
TWO
*Genetic Material DNA/RNA and
Change over time.
Are viruses living? NO