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Viruses
1.
“Virus” is the
Latin word for
poison.
2. All viruses
have one thing in
common: They
enter living
cells and, once
inside, use the
machinery of
the infected cell
to produce
more viruses.
3. A typical virus is
composed of a core
of DNA or RNA
surrounded by a
protein coat.
4. A virus’s protein
coat is called a
capsid.
5. The capsid
enables a virus to
enter a host cell.
6. Once the viral
genes get inside a
cell, the genes are
expressed.
7. This genetic
program causes the
host cell to make
copies of the virus.
8. In the process,
the host cell is
destroyed.
9. Most viruses are highly specific to the cells they infect
because plant viruses infect plant cells; animal
viruses infect only certain related species of
animals; and bacterial viruses infect only certain
types of bacteria.
10. Viruses that infect bacteria are called
bacteriophages.
11. Once a virus is inside the host
cell, two processes may occur: the
lytic cycle or the lysogenic cycle.
12. In a lytic infection, a virus enters a cell,
makes copies of itself, and causes the cell to
burst.
13. Because the host cell is lysed and
destroyed, this process is called a lytic infection.
14. A lytic virus is like an outlaw in the American
Old West because:
• The outlaw eliminates the
town’s existing authority –
(host cell’s DNA)
• The outlaw demands to be
outfitted with new weapons,
horses, and equipment by
terrorizing the local people –
(using the host cell to make
viral proteins and DNA)
• The outlaw forms a gang to
leave town to attack new
communities – (the host cell
bursts, releasing hundreds
of new viruses)
15. In a lysogenic infection, a virus integrates its
DNA into the DNA of the host cell, and the
viral genetic information replicates along with
the host cell’s DNA.
16.
17. Retroviruses are
viruses that contain
RNA as their
genetic information.
18. Retroviruses get
their name from the
fact that their
genetic information
is copied backward,
from RNA to DNA.
19. AIDS is the most
infamous retrovirus.
20. Viruses rely upon a
host to grow and
reproduce which means
they are parasites.
21. Viruses are not alive
although they can
reproduce and posses
DNA because they do
not:
1) grow and develop
2) obtain and use
energy
3) respond to the
environment
22. No. Most viruses are not harmful to humans.
23. A pathogen is a disease-causing agent.
24. Viruses cause disease by disrupting the
body’s normal equilibrium.
25. Viruses attack and destroy certain cells
in the body, causing the symptoms of the
disease.
26. No. Viral diseases
cannot be treated with
antibiotics.
27. The best way to
protect against most
viral diseases lies in
prevention, often by
the use of vaccines.
28. Most vaccines
provide protection only
if they are used before
an infection begins.
29.