Download Pathogens – Bacteria & Viruses

Pathogens – Bacteria &
Viruses
Protists & Fungi Too
A Pathogen is…
 Pathogen = Any disease causing
agent.
–Examples:
 Bacteria: Streptococcus, Staphylococcus
 Virus: HIV, Influenza (Swine Flu), The
common cold
 Protist: Plasmodium (malaria)
 Fungi: Ringworm, Athletes Foot
Viruses – Properties of Life
Properties of Life
Cellular organization
NO
Reproduction
Yes
Metabolism
NO
Homeostasis
NO
Adaption
Responsiveness
Yes
Yes
Growth and Development
NO
Virus Size
Viruses are SOOO Small!
 Too small to see with a
regular light
microscope
 Must use an electron
microscope to be
seen.
Parts of a Virus
 Capsid= “head”…protein that encloses
viral genome
 Genome= double stranded DNA OR
single stranded DNA or RNA
Viral Body Plans
 Genetic material is DNA or
RNA
 Coat is protein
head
Polyhedral virus
sheath
tail fiber
Rod-shaped virus
Complex virus
(bacteriophage)
Viruses are Obligate Intracellular
Parasites
 Obligate like an obligation – can only
replicate inside other cells
 Must live within a specific host cell –
example: cats don’t get chicken pox
 Use the host cell for replication, metabolism,
etc.
Viruses cause disease
 Influenza
– Infects the upper respiratory
tract
 Can also cause cancer
– Hepatitis B  liver cancer
– Epstein-Barr virus  Burkitt’s
lymphoma
– Human Papilloma Virus 
cervical cancer
HIV, the AIDS virus
 Glycoproteins on HIV envelope
recognize surface proteins of human
white blood cells
 RNA virus
 Includes the reverse transcriptase
enzyme
Defenses against viruses
 Skin and mucus membranes
 Inflammation (redness, swelling,
warmth and pain)
 White blood cells
 Antibodies- specific proteins that
target a specific virus
 Interferons- enzymes that prevent
the virus from replicating
Credit: © Dr. George Chapman/Visuals Unlimited
T4 Bacteriophages on Escherichia coli) bacteria. T4 bacteriophages are parasites of E. coli, a
bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by
its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the
host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X40,000.
Credit: © Dr. George Chapman/Visuals Unlimited
T4 Bacteriophages on Escherichia coli bacteria. T4 bacteriophages are parasites of E. coli, a
bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by
its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the
host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X60,000.
Bacteria - Prokaryotes
 Eubacteria = True Bacteria.
– Cell wall contains the carbohydrate
peptidoglycan
 Archaeabacteria = Ancient Bacteria.
– NO peptidoglycan in cell walls.
– MORE similar to Eukaryotes!!! (US)
– Live in harsh environments
Bacteria are very small
This is a
pore in
human skin
and the
yellow
spheres are
bacteria
Bacteria
are very
small
compared to
cells
with
nuclei
Bacteria
Bacteria
compared
to a white
blood
cell that
is going
to eat it
Clean skin has about 20 million
bacteria per square inch
Structure
 No nucleus
 No membrane
bound organelles
 DNA is circular
Plasmids
Page 546
Bacteria Shapes
Bacterial Reproduction
Credit: © Dr. Dennis Kunkel/Visuals Unlimited
E. coli is a gram-negative, facultatively anaerobic, rod prokaryote undergoing conjugation.
One strain has fimbriae. E. coli can cause urinary tract infections, traveler's diarrhea,
nosocomial infections, and a variety of skin and wound infections such as scalded skin
syndrome, scarlet fever, erysipelas and impetigo. TEM.
 Bacterial reproduction
Cellular organism copies it’s genetic information then splits into
two identical daughter cells
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Bacterial reproduction
Conjugation
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eria.jpg&imgrefurl=http://www.drnatura.com/flora_protect.php&h=248&w=389&sz=44&
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Good Bacteria
Good causing bacteria
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E. Coli in stomach aids digestion
Benefit soil
Nitrification
Decomposition
Make acetone or butanol
To produce insulin, other chemicals
Clean oil spills
To clean ore
Yogurt, cheese, olives, vinegar, sourdough
Disease causing bacteria
 Way 1: metabolize their host (destroy host
cells)
 Way 2: secrete poison as waste product
TUBERCULOSIS
STREP THROAT
LYME DISEASE
Staphylococcus
aureus
Credit: © Dr. Gary Gaugler/Visuals Unlimited
This bacteria can causes toxic shock syndrome (tampon use) and can also cause impetigo
and pyoderma and is common in infant day care centers. SEM.
Archaeabacteria