1. How do we classify viruses?
But What About Viruses?
How do we classify viruses?

2. Recall the Characteristics of Life
Made of cells
Able to reproduce
Based on a Genetic Code
Grow and develop
Respond to Environment
Maintain homeostasis
Change over time
Obtain and use energy and materials

3. Virus Most scientist do NOT consider virus particles LIVING Because:
A virus can not reproduce independently
They are not cells
Only inside of living cells can a virus:
Manipulate DNA or RNA
Change over time

4. A virus is an infectious agent made up of nucleic acid (DNA or RNA) wrapped in a protein coat called a capsid. vs

5. What is a Virus?
Viruses have no nucleus, no organelles, no cytoplasm or cell membrane—Non-cellular
This is why it does NOT belong to any kingdom.
Viruses have either DNA or RNA but NOT both.

6. Shapes of a Virus

7. Examples of Viruses Polio
Virus attacks the nervous system and can quickly cause paralysis

8. Virus Examples
Rabies
Transmission occurs through the saliva of animals
Attacks peripheral and central nervous system
Symptoms include: fever, muscle spasms, paralysis, and confusion

9. Virus Examples Human Immunodeficiency Virus (HIV) Attacks T Cells
Leads to AIDS

10. Virus Examples Smallpox
Virus attacks a variety of cells in the body, starting with the mouth and throat, eventually causing the cells to burst, creating “pox”

11. Virus Living Cell RNA or DNA core (center), protein coat (capsid)
Cell membrane, cytoplasm, genetic material, organelles
Structure
Copies itself only inside host cell--REPLICATION
Asexual or Sexual
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 NO
YES

12. Vaccines Contains a killed or weakened part of a virus
Body makes antibodies to be produced quickly if exposed again