Pathogens: Agents of Disease

1. Pathogens:Agents of Disease

2. Microbiology • 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.

3. Cells • 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.

4. Bacteria • 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)

5. 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)

6. 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.

7. Reproduction of Bacteria Video • http://www.youtube.com/watch?v=gEwzDydciWc&feature=player_detailpage • Write two questions about the clip you just saw about bacteria reproduction. • 1)? • 2)?

8. Bacteria • 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

9. 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 Lyme disease MRSA leprosy

10. Bacteria • 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.

11. Viruses • 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)

12. 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

13. 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

14. Viruses • 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)

15. 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. Ebola Small Pox

16. Viruses • 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)

17. Spread of Viruses video • Write two questions about the clip you just saw about viruses. • 1)? • 2)?

18. 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 • Shapes • Extremely diverse…most diverse of any kingdom • Reproduction • The majority reproduce by binary fission but there are a few other methods as well.

19. 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) ?

20. Fungi • Characteristics • Eukaryotic • Most are multicellular (many-celled) • Do not produce their own food (heterotrophic) • Cannot move on their own

21. 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)

22. 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

23. 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

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

25. Parasites/Helminths • 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.

26. 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.

27. Helminth Infection video • http://health.discovery.com/videos/monsters-inside-me-elephantitis.html • Write two questions about the clip you just saw about parasitic worms. • 1)? • 2)?