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Viruses and Bacteria
Viruses
• Central question----What is a pathogen? A
DISEASE-CAUSING agent.
• How are pathogens passed to others?
Infection
Definition: Viruses
• Tiny, _NON-LIVING______ particles
• Smaller than bacteria
• Nonliving characteristics
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Do _NOT_____ carry out respiration
Do _NOT_____ grow and develop
Do not metabolize
Not made of ___CELLS_____________
However, Does contain ___DNA________or RNA
Definition: Viruses
• Able to replicate inside living things called a _HOST__ cell
• Viruses are named after the diseases that they cause or the
organ or tissue that they infect. _ADENOVIRUS__causes a
common _COLD_________ and infects the adenoid tissue in
the back of the throat and nasal cavity.
Structure
• Inner _NUCLEIC_acid
core (DNA/RNA)
• 1 or 2 protein coats,
capsid which
determines shape
• 3rd – viral capsid
envelope (human
_FLU_______)
Structure
• 4 Shapes
• Polygon (polio)
• Cylindrical (tobacco
mosaic virus, plants)
• Covered in an
envelope shaded
with
__PROJECTIONS_
(influenza- human
flu, HIV)
• Bacteriophagelunar standing
module
Recognition and Reproduction
• _SHAPE____is important for replication of a virus. Viruses
recognize and attach _SPECIFIC______receptors. For example,
animal viruses attach to _ANIMAL__ cells.
• First, viruses must find a site on plasma membrane of the
_HOST______________.
• Viral protein coat is important for recognition of specific cells.
Viruses are species specific.
Recognition and Reproduction
• The 3 dimensional shape on plasma membrane of the virus
_INTERLOCKS_____ with shape on the host membrane.
• A T4 _BACTERIOPHAGE, which is a virus that attaches and
infects _BACTERIA_ uses a tail fiber to attach to E.coli.
Recognition and Reproduction
• In the 1980s the announcement of the eradication of
__SMALLPOX_ had occurred because it only infected
_HUMANS__ and doctors were able to quarantine people and
get rid of the virus. However, the flu is difficult to eradicate
because it is _NOT________ species specific AND IT CAN
CHANGE/ADAPT.
Lytic and Lysogenic Cycles
https://youtu.be/kYf_Sl8W3qY
Types of Viruses
•
Chicken pox, HPV- HUMAN PAPILLOMA VIRUS, examples of items that can be
spread through contact.
• HIV is a RETROVIRUS_ which is a virus that contains RNA and _REVERSE
TRANSCRIPTASE____. Reverse transcriptase- enzyme that copies viral RNA
into DNA. HIV is an infection of the _WHITE BLOOD CELLS_____. The
infected person’s white blood cells are damaged and their immune system
fails which lead to other diseases and that is when the disease can be
called AIDS_.
Types of Viruses
• West Nile- Caused by _INFECTED MOSQUITOES___. West Nile
Virus is a flavivirus commonly found in Africa, West Asia, and
the Middle East. It is closely related to St. Louis encephalitis
virus, which means _HEAD_ swelling which is also found in the
United States. The virus can infect humans, birds, mosquitoes,
horses and some other mammals.
Types of Viruses
•
SARS- Severe Acute _RESPIRATORY_ Syndrome. SARS was first reported in
Asia in February 2003. Over the next few months, the illness _SPREAD___ to
more than two dozen countries in North America, South America, Europe,
and Asia before the SARS global outbreak of 2003 was contained. According
to the World Health Organization (_WHO_________), a total of 8,098
people worldwide became sick with SARS during the 2003 outbreak. Of
these, 774 died. Symptoms include fever, headaches, __PNEUMONIA_.
Cause is _AIRBORNE__.
Types of Viruses
• Avian Flu- This _INFLUENZA___ virus occurs naturally among
_BIRDS___. Wild birds worldwide carry the viruses in their
intestines, but usually do not get sick from them. Avian
influenza is very _CONTAGIOUS__ among birds and can make
some domesticated birds, including chickens, ducks, and
turkeys, very sick and kill them. Infected birds shed influenza
virus in their __SALIVA_, nasal secretions, and feces. Able to
CHANGE like other flu viruses. No _PREVENTION_ available
except the H5N1 vaccine. _PANDEMIC_or worldwide problem.
Types of Viruses
• Mad cow disease is caused by a _PRION__. A prion is a
microscopic _PROTEIN___ particle SIMILAR_____ to a
_VIRUS_ but lacking nucleic acid, thought to be the infectious
agent responsible for Mad Cow disease and certain other
degenerative diseases of the _NERVOUS____system. Also
known as, BSE (bovine spongiform encephalopathy) is a
progressive neurological disorder of cattle that results from
infection.
• Read up on Swine Flu
Vaccines
• In order to prevent some viruses, there are
_VACCINES, which are injections that have
a small dose of the
_PATHOGEN______mixed into it and it
helps build up the body’s immunity against
the disease.
Bacteria
• Your bacteria pamphlet is going to be your
bacteria notes. You can X out the bacteria pages
in the packet as they are the same material.