1. Are Viruses Alive?

2. Viruses… Their Basic Structure
Have a protein capsid (“head” region)
DNA inside the capsid
Some have a tail region and tail fibers

3. What do viruses look like?
Have a protein capsid containing DNA
Tail fibers allow virus to “land” on a host cell
Injects DNA into host cell

4. Viral Dormancy
Only activate their DNA once they have infected a host cell
Can exist without a host for hours, days or longer!
“Hijacks” and uses the host cell’s organelles to make new viral copies

5. Let’s Compare CELLS VIRUSES Prokaryotic or eukaryotic
Outer cell membrane
Can divide & reproduce independently
Requires energy to survive
Produces wastes
Responds to stimuli
Have no organelles
No outer membrane
Needs a host cell to make new viral copies
No energy requirement
Produces no wastes
No response system

6. So… are there ANY similarities??
Both use DNA to make new copies
This DNA can mutate
Tiny (microscopic)

7. What happens once a virus enters a host cell?
Let’s watch how phages attack bacterial cells…