Download Virus Notes

12/4/2012
The word “virus” comes from the
Latin for “poison”.
Virus
Notes
What is a virus?
•Viruses are segments of nucleic acid (DNA or RNA)
contained in a protein coat (capsid); some also have an
envelope.
•Viruses have NO cell membrane, nucleus, or organelles.
It does not eat/metabolize.
•It is not considered to be a living thing.
•About 1/10 size of most bacteria
Phage=another word for virus
DNA viruses (like chickenpox virus) are stable.
One vaccine or exposure = lifetime protection
RNA viruses (like influenza viruses) tend to
mutate frequently. This is why a different flu
shot is produced every year. The antibodies
your body made against the virus last year do
not recognize the new, mutated virus this year.
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12/4/2012
A virus is a type of pathogen, which
means it can cause disease in
humans, animals, bacteria, and
plants.
child with chickenpox
A vaccine is a weakened or “killed”
form of the virus and helps the
immune system recognize and
destroy it the next time you are
exposed.
bacteriophage
attacking bacterial
cell
Tobacco mosaic virus
An antibody is a type of protein in your blood
and body fluids. The body's immune system
produces antibodies when it detects harmful
substances such as bacteria, fungi, parasites,
viruses, and chemicals.
How do viruses replicate?
Lytic (active)cycle - new viruses exit cell; cell is
destroyed (ruptures)
Lysogenic (inactive) cycle - viral genes integrate into
host genes and divide with host cell; cell survives
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12/4/2012
A New Class of Pathogens
Viroid = infectious RNA that cause disease in
plants
Prion = infectious proteins that cause disease in
some animals (ex: mad cow disease caused by a
prion that infects brain cells)
Examples of viruses:
bacteriophage = virus that infects
bacteria (most common is T4); used
as a vector to deliver missing genes
in patients (gene therapy)
Plant viruses – tulip break virus,
TMV (tobacco mosaic virus)
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Animal viruses – Human Immunodeficiency
Virus (HIV), colds, Ebola, Hepatitis, polio,
influenza, mumps, rabies, Severe Acute
Respiratory Syndrome (SARS)
Cancer-causing viruses:
Hepatitis B & C (HBV & HCV)
– liver Cx (cancer)
Epstein-Barr virus (EBV)lymphoma
Human papilloma virus (HPV) –
cervical cancer
Now…your assignment is to
describe and make a virus
model.
1)Make a drawing of your virus.
2) Label the two parts of your
virus (DNA or RNA and
capsid).
3) Where did it originate?
4)What host/cell type does it
infect?
5)How is it transmitted?
6)What are the effects on the
host?
7) Make a 3-D model of your
virus. Don’t forget the nucleic
acid and hanging string!
Retrovirus
Adenovirus
Bacteriophage
HIV
Rabies
Tobacco
Mosaic Virus
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