Transcript Viruses & Bacteria A virus is a nonliving particle with a simple structure. Composed of a nucleic acid (DNA or RNA) surrounded by a protein.

Viruses &
Bacteria
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A virus is a nonliving particle
with a simple structure.
Composed of a nucleic acid
(DNA or RNA) surrounded by
a protein coat.
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Virus Structure
Capsid
- The capsid is the protein
shell that encloses the nucleic acid; Three
functions:
Or
RNA
1) it protects the nucleic acid from
digestion by enzymes,
2) contains special sites on its surface
that allow the virus to attach to a host
cell, and
3) Allow virus nucleic acid penetrate the
host cell’s membrane and, in some cases,
to inject the infectious nucleic acid into
the cell's cytoplasm.
Or
RNA
Envelope
- Surrounds the capsid.
Composed of two lipid layers interspersed
with protein molecules
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Viral Nucleic Acid
•The nucleic acid of each virus encodes the genetic
information for the synthesis of all proteins.
•Only a few groups of viruses use DNA.
•Most viruses maintain all their genetic information with
the single-stranded RNA.
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Viruses, such as the influenza virus,
that have RNA as their genetic
material mutate more often that
DNA viruses.
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Lytic Cycle
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1.The virus attaches
to a host cell and
injects its nucleic
acid into the cell.
2.The viral nucleic
acid is immediately
replicated,
eventually causing
the host cell to
burst, releasing new
viral particles.
3.These new viruses
then attack other
cells.
Lysogenic Cycle
After the virus
embeds its nucleic
acid into the
chromosome of the
host cell, the viral
nucleic acid is
replicated along with
the host cell’s DNA.
Then the virus
becomes dormant,
sometimes for years
without the host
knowing.
The virus may
suddenly become
active, resuming the
lytic cycle, which
will eventually
destroy the host
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Overview:
Lytic and
Lysogenic
cycles
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Are viruses alive?
• Can They:
– Reproduce?
– Obtain and use
energy?
– Grow, develop,
and die?
– Respond to the
environment?
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Vaccines
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CLIP
•VACCINE CLIP
Diseases Caused by Viruses
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Influenza
1918 pandemic
20 to 40 million people
More people died of influenza in a single
year than in four-years of the Black
Death Bubonic Plague from 1347 to
1351. Known as "Spanish Flu" or "La
Grippe" the influenza of 1918-1919 was
a global disaster
Polio
• Polio is a contagious, historically devastating
disease that was virtually eliminated from the
Western hemisphere in the second half of the
twentieth century. Although polio has plagued
humans since ancient times, its most extensive
outbreak occurred in the first half of the 1900s
before the vaccination, created by Jonas Salk,
became widely available in 1955.
• People who have abortive polio or nonparalytic
polio usually make a full recovery. However,
paralytic polio, as its name implies, causes
muscle paralysis - and can even result in death.
In paralytic polio, the virus leaves the intestinal
tract and enters the bloodstream, attacking the
nerves (in abortive or asymptomatic polio, the
virus usually just stays in the intestinal tract).
The virus may affect the nerves governing the
muscles in the limbs and the muscles necessary
for breathing, causing respiratory difficulty and
paralysis of the arms and legs. Although the
acute illness usually lasts less than 2 weeks,
damage to the nerves could last a lifetime.
•What's the
Future of Polio?
Through intensive
vaccination
programs, a
coalition of
organizations in
1999 decided to
work toward world
eradication of
polio by 2005.
Between 1988 and
1998, wild-type
polio was
eliminated from
North America,
South America,
and Europe. But
polio still exists in
Africa, as well as
India and some of
its neighboring
countries.
Clip
People can be exposed to Ebola virus from
direct contact with the blood and/or secretions
of an infected person: contact with objects,
such as needles, that have been contaminated
with infected secretions
Human Immunodeficiency
Virus
Lassa Fever
The number of Lassa virus infections per year in West Africa is
estimated at 100,000 to 300,000, with approximately 5,000 deaths. In
some areas of Sierra Leone and Liberia, it is known that 10%-16% of
people admitted to hospitals have Lassa fever, which indicates the
serious impact of the disease on the population of this region.
Chickenpox
• Chickenpox is a very contagious viral
disease that causes an itchy
outbreak of skin blisters.
• The chickenpox virus spreads from
person to person by direct contact
with fluid from broken chickenpox
blisters.
• Chickenpox is usually a mild disease.
However, in adults and children with
weakened immune systems,
chickenpox can cause serious
complications and even death.
• A vaccine is now available to prevent
chickenpox.
Hantavirus
Measles
Diseases of childhood that causes a skin rash.
•
• Serious complications, such as pneumonia, croup or
encephalitis, can occur.
• The disease starts with a cold, fever, cough,
conjunctivitis (red eye) and fatigue. Three days later, a
red blotchy rash starts on the face - then spreads to
the rest of the body, including the feet. The fever
starts to go down on the second or third day of the
rash. There may be some fine peeling of the skin after
the rash fades. Most patients are ill for about seven
days;
• IS IT CONTAGIOUS?
VERY. It is most common in late winter and early
spring. Most people have been exposed to the disease
10-12 days before they have any symptoms. Spread by
coming in contact with the saliva of someone who has the
disease through coughing, kissing or sharing of eating
utensils.
• Once you have had a case of measles you have lifetime
immunity (protection) to the disease.
Mumps
Rabies
Most often transmitted through the bite of a rabid animal
Smallpox
• Infection usually occurred by inhalation
of virus
• acute, with fever, malaise, headaches,
and backaches. The initial toxemia phase
lasted 4-5 days. On about the third or
fourth day, the characteristic rash
appeared. First, it appeared on the
buccal and pharyngeal mucosa, the face,
and the forearms. Within a day, it
spread to the trunk and lower limbs.
• The lesions usually protruded from the
skin and are firm to touch. About 8
weeks after onset of the rash, the
lesions dried up and became crusted by
day 14. By the end of the third week,
most crusts had fallen off, with the
exception of the palms and the soles.
The outcome of infection was either
death or recovery with immunity.
In 1966, the World Health Organization started a program for the worldwide
eradication of smallpox.
Through intensive case finding and vaccination of direct and indirect contacts,
the disease was finally eradicated on December 9,1979.
Hepatitis C
Before a blood test was
discovered in 1989 to screen
for HCV, this was the most
frequent hepatitis to be
acquired from blood
transfusions and blood
products.
Up to half of those with
chronic disease will go on to
develop liver failure and need
a transplant.
Each year, 8,000 to 10,000
people die in the United
States because of hepatitis
C-related cirrhosis or HCVrelated liver cancer.
Hepatitis B
This type is essentially a
blood-borne virus with other
bodily fluids being infectious,
notably semen and saliva, and
is often transmitted from
mother to fetus.
Hepatitis
Hepatitis is a disease
that impairs liver
function either
temporarily or
permanently,
sometimes even
leading to death. It
can be initiated by a
host of factors, but
primarily by viruses.
Drugs also can cause
hepatitis but when
the specific drug is
discontinued, the
liver usually returns
to normal.
Herpes
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Infection caused by the Herpes Simplex
Virus (HSV), which resides in the nerve
ganglia after the initial exposure to the
virus.
Because the virus is so effective at "hiding
out" in the nerve cells, the body is never
able to eliminate the herpes virus
completely. Instead, after the initial
infection, the body produces antibodies
which show up in the blood stream.
Blood tests which indicates the presence or
lack of these antibodies.
The antibodies make it easier for the body
to recognize and attack the virus when it
re-emerges from the nerve cells in the
form of an outbreak.
For this reason, out breaks following the
primary outbreak usually diminish in
frequency and intensity over time.
Some people may never have another
outbreak.
•How germs are
spread
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EXTRAS
• Prion-is a type of infectious agent made
only of protein.
• Chronic wasting disease, (in deer and elk),
mad cow disease
• All of these diseases affect the structure of
the brain or other neural tissue, and all are
untreatable and fatal.
• Viroids-small naked single-stranded RNA
molecules that infect plant cells and cause
disease.
• Smaller than viruses, viroids are not
enclosed in a protein coat of any kind.
• They generally consist of less than 400
nucleotides and do not contain any genes.
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MONERA
EUBACTERIA
1.Largest
2.Unicellular
3.Prokaryotic
4.Most use oxygen
but some are
anaerobic.
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ARCHAEABACTERIA
1.Unicellular
2.Prokaryotic
3.Ancestors of
Eukaryotes
4. Lives in harsh
environments.
Round
Rod
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Spiral
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Gram Staining
Method scientist use to
determine cell wall type in
bacteria
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Nutrition
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Releasing Energy
Obligate
Aerobes
Must Have
Oxygen
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Facultative
Anaerobes
With or
Without Oxygen
Obligate
Anaerobes
Cannot Have
Oxygen
Bacteria Reproduction
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Sexual
Asexual
Conjugation
Binary Fission
Exchange DNA
Split
E. coli undergoing conjugation
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Endospores are a method of survival.
ENDOSPORE FORMATION
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BACTERIA
HELPFUL
Soil---decomposing
HARMFUL
Diseases
Plants---nitrogen fixation
Humans---digestive system
Humans---Food:cheese, yogurt, sauerkraut, & soy sauce.
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Photosynthesis produces oxygen
Diseases caused by Bacteria
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Bacterial Diseases
release
poisons
that
Harm
the
body
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breaking
down
tissues
for
food
Alexander Fleming
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antibiotics can be
used to destroy
bacterial cells
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There are different ways to prevent a bacterial infection.
1. Skin and surfaces that have been in contact with raw meat should be
washed thoroughly, food should be cooked properly, and contaminated
water should be boiled.
2. Avoid contact with an infected organism or organisms that carry diseasecausing microorganisms.
• Plague swept across Europe in the Middle Ages, half of the
population died.
• Bacteria transmitted through the bite of a flea.
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EOCT
QUESTIONS
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The outer layer of a virus is
made of
A)
B)
C)
D)
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carbohydrates
lipids
nucleic acids
proteins
A vaccinations
B blood transfusions
C vitamin C
D antibiotics
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A
B
C
D
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bacteria
fungi
protozoa
viruses
Why is food preserved by canning in glass
containers normally safe for later
consumption?
A The glass allows solar radiation to kill
the bacteria that were in the food.
B Bacteria are destroyed by extreme
heat in the glass container.
C Bacteria are removed from the food
before it is placed in the glass container.
D The glass container prevents oxygen.
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