1. Latin for
“poison”
A virus is a particle that can only be
seen with an electron microscope. 1

2. Viruses are not cells and are not made-up
of cells. They live only within a living cell
and have no attributes of a living organism
They don’t…
 Contain a nucleus or cytoplasm
 Eat
 Grow
 Carry on respiration
 Or perform other biological functions 2

3. • A virus is made up
of genetic material
inside a protein
coat
• Viruses do not
carry on most
metabolic
activities
• Viruses that only
attack bacteria are
called
bacteriophages 3

4. A virus is surrounded by a capsid (protein
coat) which determines the shape of the
virus.
The capsid contains
nucleic acids
(either DNA or RNA).
Tail fibers
for attachment
to host cell. 4

5. Viruses are classified by:
 type of host cell
 presence of DNA or RNA (retroviruses)
 shape:
Binal
Polyhedral 5
Filo

6. Naming Viruses
• After the disease • Organism it
it causes (ex. affects (ex.
Polio) Tomato Mosaic)
6

7. • People who
• Place where it’s
identify it (ex.
found (ex. Ebola) Epstein-Barr
virus)
7

8. • Viruses and bacteriophages invade cells
and use the host cell's machinery to
synthesize more of their own
macromolecules.
• Once inside the host the bacteriophage or
virus will either go into a Lytic Cycle-
destroying the host cell during
reproduction.
or
• It will go into a Lysogenic Cycle - a
parasitic type of partnership with
the cell

9. VIRAL REPLICATION
Viruses replicate in one of two ways:
• Lytic
• Lysogenic
9

10. Virus attaches to
LYTIC CYCLE
host cell.
Virus injects its
DNA
Cell lyses (breaks
apart) and new
viruses are
released
Virus DNA
commands host cell
to make new viral
parts
New viral parts
assembled
10

11. 11

12. LYSOGENIC CYCLE
12

13. LYSOGENIC CYCLE
• Does not begin immediately
• Viral DNA (called a prophage)
attaches to the host cell’s
chromosomes – lies dormant.
• The virus DNA integrates with the
host DNA and the host’s cell helps
create more virus DNA.
• Environmental stimulus sends viral
DNA into lytic cycle. 13

14. VIRAL DISEASES
Disease Transmission Symptoms
AIDS/HIV Sexual contact; Immune system failure;
contaminated blood fatal
or needles
Common Inhalation, direct Sinus congestion, muscle
Cold contact aches, cough, fever
SARS Inhalation, direct Headache, discomfort,
contact body aches, chills
Influenza Inhalation Headache, muscle ache,
(Flu) sore throat, cough, fatigue,
fever, chills
HPV Sexual contact Warts, may cause cervical
cancer
Herpes Direct contact Open sores on mucus
membranes 14

15. 15

16. Most viruses have
NO cure
(Influenza, & HIV),
but some viruses
like Small- pox
have vaccines.
Vaccines contain a weakened or killed
virus that provides immunity to the
disease. 16

17. • http://acms7science.weebly.com/uploads/5/
2/4/8/5248911/viruses.ppt.pdf
• http://freedownload.is/ppt/bacteria-and-
viruses-21171792.html
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