SMART
The Virus
What they are and how they work
What is a virus
Viruses are
particles of nucleic
acids, proteins,
and in some
cases, lipids.
Are parasites
*Virus is the Latin
word for poison
*Are they alive?
Living things:
– Are made up of cells NO
NO/YES
– Reproduce
– Based on a universal genetic code YES
– Grow and develop No
– Obtain and use materials and energy NO
– Respond to their environment NO
– Maintain stable internal environment NO
– Change over time YES
Viral Structure
Basic Structure:
– DNA or RNA core
– Protein coat =
capsid
Sketch this T4
Bacteriophage
Other structures
Tobacco Mosaic Virus
Lytic Infection
Lytic Infection:
Virus enters a
cell, makes
copies of itself,
and causes
the cell to
burst
*Lyse = burst
Lysogenic Infection
Lysogenic Infection: A virus integrates its
DNA into the DNA of the host cell, and the
viral genetic information replicates along
with the cell’s DNA
Ex: Herpes simplex
Lytic vs. Lysogenic
Retroviruses
“retro-” means backwards
Retroviruses use RNA
– Produce DNA copy in cell of their RNA
– DNA is inserted into host DNA
– Can remain dormant
Ex: HIV/AIDS
Retrovirus = Hard to fight
Bacteriophage
Bacteriophage is a virus which attacks a
bacteria!
* “phage” = Greek = eating
I am sick with a virus can I have
some antibiotics?
*NO!!!!
Antibiotic means against life . . . Viruses
aren’t living!!!!
We can vaccinate beforehand, but once
you are sick with a virus, Dr.’s can only
give you stuff for symptoms.