VIRUSES
A tiny, non-living parasite (particle) that enters and reproduces inside a living host cell.
Two types: 1. Active2. Hidden
Characteristics of Viruses
Non-living Parasite Not a cell Cannot make or take in their own food Does not produce waste Multiply only in living cells
Shapes of Viruses
Round (chicken pox, west nile) Tube/rod shaped (tobacco mosaic) Bullet (rabies) Robotlike (bacteriophage) Brick or thread like (Ebola)
Virus Size
Smaller than cellsMeasured in nanometers (nm)
Question: Which is larger Bacterium or Influenza Virus?
Naming Viruses
For the diseases they cause For the organism they infect After the person who discovered them
Virus Structure
Two basic parts Protein coating – protects the virus Inner core – genetic material
Some may also contain a membrane envelope.
ACTIVITY:
DRAW AND LABEL THE PARTS OF A VIRUS.ADD COLOR
How Active Viruses Multiply
1. Attaches to host cell
2. Virus genetic information enters host cell
3. Viruses takes over host cell functions (becomes a bacterium)
4. Virus proteins and genetic information reproduces
5. Host cell burst open releasing new virus
Active viruses are always working and multiplying Examples: cold, flu
How Hidden Viruses Multiply
1. Attaches to host cell2. Injects Virus genetic material3. Virus genetics becomes the host’s cells genetics4. Virus genetic material becomes active5. Takes over cell functions6. Host cell burst releasing virus
Stays inactive for several years (hide & attack) When host cell divides so to does the virus
genetics Example: Cold Sore
Viruses in Our Living World
Viruses & Disease People:
Cold – short lived – active AIDS - Hidden
Plants: Animals:
Rabies Distemper
Usefulness of Viruses Gene Therapy – used to treat Cystic Fibrosis
Examples of Common Viruses
Polio Chicken pox Smallpox Yellow fever Viral Meningitis West Nile Ebola
PolioPolio
Chicken poxChicken pox
Chicken pox
Small PoxSmall Pox
Yellow Fever
Viral MeningitisViral MeningitisWest NileWest Nile
Ebola
Yellow Fever
Summarize
What is a Virus? Identifying basic structure and traits.