1. Viruses

2. What Is A Virus
A microscopic parasite that infects cells in biological organisms.

3. Do Viruses Live Viruses are considered neither alive nor dead
Viruses a HOST
Can reproduce only by invading and controlling other cells as they lack the cellular machinery for self-reproduction
Performs no cellular functions on its own.

4. Viruses Are Parasites
Viruses are parasites, meaning they cannot survive and thrive without a host or group of host cells.
The hosts provide viruses with all the chemicals and molecules they need to survive and reproduce.
Viruses are completely dependent upon other organisms to function.

5. Physiology Consists of: A strand of genetic material
An outer protective protein coat called a CASPID
Tail fibres that allow the virus to anchor onto host cells

6. Viruses are Specific Specific viruses infect specific cells
Example: The Influenza Virus attacks the cells in the respiratory system and is responsible for flu
Example: Human Immunodeficiency Virus (HIV) attacks the white blood cells of the human immune system

7. Virus Shapes Viruses can be classified by their shape
Examples of virus shapes are:
Retrovirus
Bacteriophage
Andeovirus
Pox Virus
Tobacco Mosaic Virus

8. Retrovirus HIV destroys white blood cells
The loss of these cells impedes the ability of the immune system to fight infection
AIDS occurs when the body’s immune system has collapsed and the body is open to infection

9. Bacteriophage Bacteriophages are bacteria “eaters”.
They attack and destroy bacteria

10. Adenovirus The common cold is caused by the Rhinovirus
Symptoms include coughing, sneezing, sore throat and a runny nose
No cure for the common cold except for rest and lost of fluids

11. Tobacco Mosaic Virus

12. Pox Virus
Small Pox
Attacks blood vessels in the skin and around the mouth and throat
Causes rashes and fluid filled blisters

13. Ebola Virus

14. Foot and Mouth Disease
Highly contagious, from cattle and pigs

15. SARS
Severe Acute Respiratory Syndrome

16. Replication There are generally 4 steps to replication
Attachment and Entrance
Synthesis of protein and genetic material
Assembly of the new viruses
Release of new virus particles

17. Replication

18. Replication

19. Replication The process is known as the LYTIC CYCLE
LYSIS: The destruction or bursting open of a cell.
This leads to the releasing of viruses from a cell.

20. Replication
Can be completed in as little as min and can reproduce hundreds of new viruses under ideal lab conditions

21. Lysogenic Cycle
Viruses can lie dormant within any host or environment until the proper conditions for their activity are provided.
LYSOGENY: the dormant state of a virus
The virus’ genetic material becomes integrated into cell and is replicated to all daughter cells until activated by a stimulus

22. Activation
Can be caused by environmental changes like temperature or pH
Can be caused by changes in available nutrients
The above can trigger the lytic cycle and new viruses are formed and released

23. Viruses As Pathogens
Viruses attack cells as they reproduce killing the host cells
The destruction of these cells causes symptoms of diseases
Antibiotics do nothing to stop viruses

24. Vaccines
Made from dead or weakened viral cells can stimulate the body to fight viruses