pathogens: agents of disease - weebly
TRANSCRIPT
Microbiology is the study of microorganisms.
Microorganisms are mostly unicellular (single-
celled) organisms too small to be seen
without a microscope. They include viruses,
bacteria, protozoa, and some fungi.
Microorganisms that cause disease or harm to
living things are called pathogens.
Microbiology
All cells contain genetic material known as
DNA or RNA.
There are two major types of cells:
Prokaryotes--Prokaryotic cells have no nucleus—
their genetic material is found as coiled strands in
the cytoplasm.
Eukaryotes--Eukaryotic cells have a distinct,
membrane-bound nucleus that contains the DNA
and RNA of the organism.
Cells
Characteristics
Oldest forms of life on Earth
Unicellular (single-celled) organisms
Prokaryotic
Contain DNA (genetic material)
Can live in a variety of places (with or without
oxygen; extreme temperatures)
Bacteria
Shape
Most have rigid cell walls that give it shape
Bacteria come in one of 3 shapes rod (bacilli),
sphere (cocci), or spiral (spirilla)
Bacteria
Reproduction
Bacteria can reproduce quickly by a process
called binary fission where one bacterium
divides into two bacteria (in essence cloning
itself). *There are other forms of reproduction
Will grow in colonies (a group of many that
can be seen by the naked eye)
Their reproduction is slowed down by cold
(refrigeration or freezing), heat
(pasteurization and sterilization), and salting.
Bacteria
http://www.youtube.com/watch?v=gEwzDydci
Wc&feature=player_detailpage
Write two questions about the clip you just
saw about bacteria reproduction.
1)?
2)?
Reproduction of Bacteria Video
Role in the World Good for the Environment
Nitrogen cycle
Decomposition
Good for the People
In food…cheese, yogurt, buttermilk, sour cream, etc.
Medicines…fighting other bacteria, antibiotics, insulin
Genetic Engineering…change genes of bacteria to make insecticides, cleansers, adhesives, etc
Bacteria
Role in the World continued…
Harmful Bacteria (pathogenic—disease causing)
Infectious bacterial diseases…tuberculosis, Lyme disease, MRSA, leprosy, strep, etc. *infectious
means it can be passed from one organism to another
Bacteria
Lyme disease MRSA
leprosy
Role in the World continued…
Pathogenic (infectious disease) continued…
Can be treated with antibiotics--medicines taken by an infected person to kill the bacteria in the body (penicillin, amoxicillin, tetracycline)
Some antibiotics have been overprescribed and by natural selection, bacteria have become resistant (can’t be killed) to certain medications. This is known as antibiotic resistance. Mutant bacteria survive antibiotic treatment and a resistant population survive.
Can be prevented with vaccinations—substances that stimulate the body to produce chemicals (antibodies) that destroy familiar invaders.
Bacteria
Characteristics
Viruses are not living
They are non-cellular
Cannot reproduce on their own
Do not use energy, need food or create waste
Contain DNA or RNA (genetic material) and protein coat
Viruses are significantly smaller than bacteria (5 billion virus particles can fit in a single drop of blood)
Viruses
Shapes
Four main shapes: crystals, spheres, cylinders, and
bacteriophages (one that infects bacterial cells
only)
Viruses mutate and change their shape all the time
though
Viruses
Viruses
Reproduction Can only reproduce inside a host cell which it often
destroys
Can add their genetic material to a host cell that stays inactive for a very long time
Role in the World
Good for the Environment
Population control…limiting factor
Good for People
Can be manipulated to create medicines and treat
some diseases (very new technology)
Viruses
Role in the World continued…
Harmful Viruses (Pathogenic)
Infectious viral diseases…HIV, Chicken Pox,
Hepatitis A, B, & C, Small Pox, Ebola, Rabies, Swine
Flu, Influenza, Common Cold, etc.
Viruses
Ebola
Small Pox
Role in the World continued…
Harmful Viruses (infectious diseases) continued…
Most viral infections cannot be cured with
medications…only symptoms can be treated
Viral diseases are amongst the most widespread
illnesses in humans
Anti-viral medications are used to control and
prevent the spread of some viral diseases, but they
do not destroy the virus (they only inhibit its
development)
Many can be prevented with vaccinations (like
bacterial infections)
Viruses
Protozoa
Characteristics
Unicellular (single-celled) eukaryotic organisms that
are usually able to move on their own
Most are found in moist environments
Although there are over 20,000 species, very few are
pathogenic
Reproduction
The majority reproduce by binary fission but there
are a few other methods as well.
Shapes
Extremely diverse…most diverse of any kingdom
Protozoa
Role in the World
Good for the Environment
Form the foundation for food chains
Play an important role in nutrient recycling
Harmful Protozoa (pathogenic)
Infectious disease transmitted by protozoa…Malaria,
Giardia, Toxoplasmosis
http://animal.discovery.com/tv-shows/monsters-inside-
me/videos/malaria-parasite.htm
Write two questions about the clip you saw
1) ?
2) ?
Characteristics
Eukaryotic
Most are multicellular (many-celled)
Do not produce their own food (heterotrophic)
Cannot move on their own
Fungi
Reproduction
Sexual reproduction—requires two individuals and
ensures genetic diversity
Asexual reproduction—one individual produces
genetically identical organisms
Spores are dormant reproductive cells; they are thick-
walled and highly resistant so they can survive
unfavorable conditions. When conditions become
suitable they give rise to new individuals and can be
used in either form of reproduction for fungi
(depending on species)
Fungi
Role in the World
Good for Environment
Important in nutrient cycles; decomposition
Food source
Good for People
Production of medicine
Production of foods (cheese, bread, beer, etc.)
Some can convert insecticides, herbicides, etc. into CO2,
H2O, and basic elements
Fungi
Role in the World continued…
Harmful Fungi
Responsible for food spoilage
Many humans are highly allergic
Fungal infections/diseases--ringworm, yeast infections,
Athlete’s foot, fungal meningitis
Fungi
A parasite is an organism that lives on or in the body
of another organism—the host.
Parasites have special adaptations or body parts that
allow them to feed off their host very efficiently—get
the most they can from them.
Examples of parasites are leeches, ticks, mosquitoes,
fleas and even mistletoe in plants.
All of the above have the ability to carry or transmit
disease or eventually cause disease in the organism
they have a parasitic relationship with.
Parasites/Helminths
Some parasites that play a large role in infectious
disease are called helminths
Helminths are parasitic worms that usually live in soil
and invade human or other animals
Includes tapeworms, roundworms, pinworms, and
Trichina spiralis (causes trichinosis from eating
undercooked pork)
Symptoms often mimic that of viral and bacterial
infections in early stages of infection but eventually
lead to more serious systemic problems because
these worms can hide in intestines, bloodstream or
any tissue of the body.
Parasites/Helminths
http://health.discovery.com/videos/monsters-
inside-me-elephantitis.html
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saw about parasitic worms.
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2)?
Helminth Infection video