Pathogens:Agents of Disease

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=gEwzDydciWc&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

EbolaSmall 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

Write two questions about the clip you just saw about viruses. 1)? 2)?

Spread of Viruses video

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

Write two questions about the clip you just saw about fungi. 1)? 2)?

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

Write two questions about the clip you just saw about parasitic worms. 1)? 2)?

Helminth Infection video