Viruses and Bacteria
What do these diseases have in common?
Mumps
http://www.kcom.edu/faculty/chamberlain/Website/lectures/lectu
re/IMAGE/MUMPS.GIF
Hepatitis B
http://www.idph.state.il.us/images/hepatitisb.jpg
Measles
http://www.idph.state.il.us/images/measles.jpg
Polio
http://www.immune.org.nz/site_resources/Prof
essionals/Diseases/Polio/Polio.jpg
It looks alive, acts alive…
but its not!
Viruses are not living things. They differ
from living things in several ways:
They need to be inside a living organism to
reproduce themselves.
Outside the cell, they have no metabolism.
They do not have cell parts. (i.e. nucleus,
mitochondria, etc)
They are composed of only a nucleic acid
(DNA or RNA) inside a protein capsule.
Structure of a Virus
DNA
Protein
capsid
(or RNA)
Tube
http://mrsec.wisc.edu/Edetc/technologist/thumbnails/Matt/Virus_diagram.jpg
Tail
Fiber
http://www.humanillnesses.com/images
/hdc_0001_0001_0_img0008.jpg
http://www.aidsactioncoalition.org/images/hiv_virus.gif
Viral Reproduction
In order to reproduce:
A virus attaches to a host cell.
The virus injects the cell with its DNA.
The viral DNA commands the cell to make more viral
protein and DNA.
The cell then ruptures, releasing hundreds of new
viruses.
http://porpax.bio.miami.edu/~cmallery/150/
gene/sf11x1virus.jpg
No, they aren’t from the 70’s.
Retroviruses
These are viruses that store their genetic
information as RNA.
Example: HIV
http://international.ucla.edu/cms/images/hiv_virus.jpg
HIV
 Infects white blood cells
 Newly made viruses are
released into blood
stream by exocytosis
and infect other with blood
cells
Self Check: What is
exocytosis?
 Since it is a provirus, cells
still function normally.
Therefore a person may
appear healthy, but can
still transmit the virus.
How it
works……
•Uses RNA to create a
copy of its DNA.
•Inserts the DNA copy
into the cell of the
host.
•Retroviruses can
remain dormant for
varying lengths of time
before they become
active.
http://hiv.buffalo.edu/./images/hiv_virus_in_action.jpg
Viral Reproduction Cycles
 Lytic Cycle: A virus
enters a cell, makes
copies of itself, and
causes the cell to burst.
 Lysogenic Cycle: 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.
Prophage: The viral
DNA that is embedded
in the host’s DNA.
(Provirus)
Virus Overview
Defining Characteristics
Protein Coat
DNA or RNA Core
Must have a host to reproduce
Examples of diseases caused by
viruses: Common Cold, Flu, AIDS,
Smallpox, Polio, West Nile, Hepatitis,
Chickenpox
Chicken pox
May remain in your
body as a provirus and
reoccur later in life as
Shingles if they enter a
lytic cycle
Other Common Viruses
The papilloma virus causes warts like
those found commonly on hands and
fingers.
Bacteria and Archaea
 Bacteria are living, unicellular
prokaryotes.
 Divided into two kingdoms:
Eubacteria and Archaebacteria
Heterotroph or autotroph (most use
chemosynthesis).
 Types of Bacteria are classified
based on their shape, type of cell
wall, and movement.
http://fig.cox.miami.edu/~cmallery/150/proceuc/c27x3p
roc_shapes.jpg
Bacterial Shapes
Bacilli: rod shaped
Cocci: spherical
Spirilla: spiral, corkscrew
Binary Fission
 When a bacteria
grows so that it
has doubled in
size, it replicates
its DNA and
divides in half
 Is this sexual or
asexual?
 Identical or different
daughter cells?
Conjugation
Some bacteria are able to exchange
genetic information
A hollow bridge forms between two
bacteria and genes move from one cell
to the other
Increases genetic diversity of a population
Spore Formation
Spores are formed when the bacteria
produces a thick internal wall that
encloses the DNA and part of the
cytoplasm
Why do you think this would be beneficial
for bacteria?
Spore Formation
Occurs when conditions are
unfavorable for growth
Can remain dormant for years until
conditions improve
We’re not all bad….
 Bacteria are most widely known for causing
diseases such as strep throat, tetanus,
meningitis, and tuberculosis.
 However, most bacteria are very useful:
E. coli helps us digest our food.
Many are important decomposers in our
ecosystem.
Rhizobium provides plants with nitrogen.
A few bacteria are used to clean up small oil
spills in the ocean.
http://www.youtube.com/watch?v=VXoz8xpwJbU
But some of us are…
 Pathogens: disease causing agents.
 Bacteria produce diseases in 2 ways:
Damage cells and tissues of infected organisms by
breaking them down for food.
Release toxins (poisons) that travel throughout the body
interfering with the normal activity of the host.
 Examples of diseases caused by bacteria:
Lyme Disease, Tetanus, Diptheria, Bacterial
meningitis, Strep throat, Tooth decay
Strep Throat
Strep throat is caused by Group A Streptococcus bacteria. It is the most common bacterial infection of
the throat.
Symptoms may be mild or severe.
You usually start to feel sick about 2 to 5 days after
you come in contact with the bacteria.
Symptoms usually begin suddenly, and can include:
•Fever that begins suddenly and is often highest on the second day
•Red throat, sometimes with white patches
•Sore throat
•Headache
•Nausea
•Chills
•General ill feeling
•Loss of appetite and abnormal taste
•Swollen lymph nodes in the neck
•Difficulty swallowing
Some strains of strep throat can lead to a scarlet
fever-like rash. This rash is thought to be an allergic
reaction to toxins made by the strep bacteria.
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001663/
Tuberculosis
 Pulmonary tuberculosis (TB) is
caused by the bacteria
Mycobacterium tuberculosis (M.
tuberculosis). You can get TB by
breathing in air droplets from a
cough or sneeze of an infected
person. In the United States, most
people will recover from primary
TB infection without further
evidence of the disease. The
infection may stay asleep or
inactive (dormant) for years.
However, in some people it can
reactivate.
Symptoms

The primary stage of TB usually doesn't cause
symptoms. When symptoms of pulmonary TB
occur, they may include:
 Cough (usually cough up mucus)
 Coughing up blood
 Excessive sweating, especially at night
 Fatigue
 Fever
 Unintentional weight loss
 Other symptoms that may occur with this
disease:
 Breathing difficulty
 Chest pain
 Wheezing
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001141/
Tetanus
Clostridium tetani produces endospores
which can enter deep cuts or wounds on
the skin.
Since these wounds can be hard to clean,
the endospores can germinate and produce
a toxin that the blood carries to the nerve
cells in the spinal cord.
Tetanus is the immunization used to treat
this.
Causes joint stiffening also known as “lock
jaw”.
Lyme Disease
Lyme disease is caused by bacteria
called Borrelia burgdorferi (B.
burgdorferi). Blacklegged ticks carry
these bacteria. The ticks pick up the
bacteria when they bite mice or deer
that are infected with Lyme disease.
You can get the disease if you are
bitten by an infected tick.
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH00022
96/
Dental Cavities
 http://www.webmd.com/oralhealth/guide/dental-health-cavities
 Cavities occur as a result of
tooth decay.
 Tooth decay is the destruction
of tooth structure. Tooth decay
can affect both the enamel (the
outer coating of the tooth) and
the dentin (the inner layer of
the tooth).
 Tooth decay occurs when
foods containing
carbohydrates (sugars and
starches) such as breads,
cereals, milk, soda, fruits,
cakes, or candy are left on the
teeth. Bacteria that live in the
mouth digest these foods,
turning them into acids. The
bacteria, acid, food debris, and
saliva combine to form plaque,
which clings to the teeth. The
acids in plaque dissolve the
enamel surface of the teeth,
creating holes in the teeth
called cavities.
Cholera
 Cholera is caused by the bacterium Vibrio
cholerae. The bacteria releases a toxin that
causes increased release of water in the
intestines, which produces severe diarrhea.
 Cholera occurs in places with poor sanitation,
crowding, war, and famine. Common locations
for cholera include:
 Africa
 Asia
 India
 Mexico
 South and Central America
 People get the infection by eating or drinking
contaminated food or water.

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001348/
 Botulism is a rare but serious
illness caused by Clostridium
botulinum bacteria. The bacteria
may enter the body through
wounds, or they may live in
improperly canned or preserved
food.
 It produces spores that survive in
improperly preserved or canned
food, where they produce toxin.
When eaten, even tiny amounts
of this toxin can lead to severe
poisoning.
 The foods most commonly
contaminated are home-canned
vegetables, cured pork and ham,
smoked or raw fish, and honey or
corn syrup.
 Botulism may also occur if the
bacteria enter open wounds and
produce toxins there.
 About 110 cases of botulism
occur in the U.S. per year. Most
of the cases are in infants.

http://en.wikipedia.org/wiki/Botulism
Vaccinations
A weakened form of the pathogen
(virus/bacteria) is used to
stimulate the production of
antibodies.
http://www.biojobblog.com/vaccination%5B1%5D.JPG
However, bacteria and viruses
have very high reproductive rates,
which result in many mutations.
Thus, bacteria and viruses evolve
quickly, often requiring a different
vaccine every year.
http://www.biojobblog.com/vaccination(5).jpg
Antibiotics
Antibiotics block the growth and
reproduction of bacteria
Used to treat bacterial infections