Disease Unit

1. Disease Unit Ms. Powell’s 8th Grade Science Class

2. Types of Disease Causing Organisms • Virus • Bacteria (includes Rickettsia) • Protozoa (includes trypanosomes) • Fungus • Worms

3. Viruses • A small nonliving particle that invades and reproduces inside a living cell • Considered nonliving because: • Viruses are not made of cells • Do not use energy to grow and develop or to respond to their environment • Do not make food, take in food or produce waste • Have ability to multiply when inside a living cell

4. Virus Vocabulary • Host:a living thing that provides a source of energy for a virus or other organism • Parasite:organisms that live on or in a host and cause harm to the host • Active virus: enters a cell and immediately begins to multiply • Hidden virus: the genetic material lies dormant in a cell for a period of time before becoming active • Ex. Cold sore virus (Herpes) lies dormant in nerve cells

5. Potential Hosts of Viruses • No organisms are safe from viruses • Viruses can attack: • Plants, Animals, Bacteria, Protists, Fungi • Viruses are generally very host specific • Ex. A plant virus does not attack people

6. Naming Viruses • Viruses are not living organisms • Scientists name the virus for the disease it causes • Ex. Polio • Scientists name the virus for the organism it infects • Ex. Tomato mosaic virus • Scientists name the virus after themselves • Epstein–Barr virus ( causes mono)

7. Virus Appearance • Very small (smaller than a bacteria -750 nm) • 22 to 250 nanometers • Shape: round, rod shaped, bricklike, threadlike, robotlike or bulletlike

8. Structure of a Virus • Two basic parts: • Outer coat that protects the virus • Made of protein • Protein shape allows virus to lock onto certain cells • Cell surface and virus coat is like a “lock and key fit” – makes virus specific to certain cells • Inner core made of genetic material • Analogy: chocolate covered cherry

9. Structure of Viruses

10. Parts of a Virus

11. Virus Photos

12. Rhinovirus (Common Cold)

13. Hepatitis B

14. How Viruses Multiply • Once inside the cell the virus’s genetic material takes over the cell’s functions • The genetic material tells the cell to produce the virus’s proteins and genetic material • These proteins and genetic material are assembled into new viruses that are released from the cell

15. How Viruses Multiply

16. How HIV Invades a Human Cell

17. Herpes zoster Shingles/Chickenpox

19. Virus: Smallpox

20. Polio Virus: Neuromuscular Damage

21. Bacteria • Are unicellular microorganisms. • Are typically a few micrometres long • Are prokaryotes – their cells do not have nuclei • Shapes: spherical, rodlike or spiral

22. Rod Shape, Spherical, Spiral Bacteria

23. Bacteria • Two types: • archaebacteria – ancient bacteria • Live in hot springs and other extreme environments • Eubacteria – live everywhere else

24. Bacteria (blue and purple rods) and other microorganisms lurk in a kitchen sponge

25. Bubonic Plague: Bubos –swollen gland

26. Rickettsia • Rickettsia species are a type of bacteria • Are carried as parasites by many ticks, fleas, and lice • Cause diseases such as Rocky Mountain spotted fever, and typhus in humans

27. Rickettsia: Lyme Disease: “Bull’s Eye” Rash at Site to Tick Bite

28. Rickettsia: Rocky Mountain Spotted Fever Rash

29. Rocky Mountain Spotted Fever

30. Typhus

31. Protozoan Parasites • Protozoa (in Greekproto = first and zoa = animals) are single-celledeukaryotes (organisms whose cells have nuclei) • Commonly show characteristics usually associated with animals • Most notably mobility and heterotrophy

32. 4 Types of Protozoa • Dinoflagellates • Cilliates • Sporozoans • Amoeba

33. 4 Types of Protozoa - Locomotion • Flagellates are cells with one or more whip-like tail called flagella. (trypanosomes?) • Ciliates –usehair-like cilia to move (malaria) • Amoeba move by means of temporary projections called pseudopods, • Sporozoans spore-forming, parasites of animals. Motile structures such as flagella or pseudopods are absent

34. Protozoa: Life Cycle of Malaria

35. Mosquito Transmission of Malaria

36. Protozoa - Trypanosomes • Undergo a complex lifecycle which may include several different morphological forms • Often transmitted by invertebrates. • African Sleeping Sickness/Tsetse fly • Chagas Disease, Triatome bug

37. Tsetse Fly

38. African Sleeping Sickness

39. Trypanosome and Red Blood Cells

40. Trypanosomiasis – Parasite Seen in Blood Sample

41. Fungal Diseases • Eukaryoticorganisms (nucleus in cell) • Digest their food externally, absorbing nutrientmolecules into their cells. • Related to yeasts, molds, and mushrooms • Ringworm, Athletes foot, Nail fungus

42. Fungus: Ringworm

43. Helminths - Parasitic worms • Intestinal parasites - tape worm, pin worm • Onchocerciasis/River Blindness is an infection caused by the parasite Onchocerca volvulus (worm) • Spread by the bite of an infected blackfly. • Lymphatic filariasis

44. African River Blindness - ParsiticWorm

45. Parasitic Worm: Lymphatic Filariasis

46. Parasitic worm

47. Parasitic Worm: Liver Fluke