Chapter 7: Infection and disease 1 EL: To explore what a disease is and what causes them

1. Chapter 7: Infection and disease 1EL: To explore what a disease is and what causes them

2. Study design – key knowledge • detecting ‘self’ and ‘non-self’ molecules: antigens and membrane receptors – pathogens: non-cellular agents, cellular agents; controls; • physical and chemical barriers to infection in plants and animals; • immune response – structure and overall function of the lymphatic system – non-specific: inflammatory response; phagocytosis; blood clotting – specific immune response: T-cell lymphocytes and cell-mediated response; B-cell lymphocytes and humoral response, antigens and antibodies; memory cells; • disorders of the immune response: autoimmunity; hypersensitivity, allergens and allergic responses; • acquired immunity: natural, artificial including vaccines and antibody serums.

3. Chapter 7: Pre-test

4. Disease • Any condition that interferes with how an organism or any part of it functions • Can be acquired through: • Genetic causes – inherited from parents • Pathogens and parasites

5. Pathogens • disease causing organism or agent (frequently but NOT always a MO) • Non-cellular pathogens • Prion • virus • Cellular pathogens • bacteria • fungi • protozoa • exo- and endo-parasites

7. Nature of Disease • Intensity of pathogenic effect: VIRULENCE • Due to special characteristics of the pathogenic organism, such as ability to produce toxins • Individuals level of susceptibility to pathogen: RESISTANCE • Varies with age, state of health, immunity • Some pathogens are able to survive outside the host, others are not • Time between infection and symptoms: INCUBATION PERIOD • Depends on pathogen achieving sufficient numbers, reaching target tissue, toxin accumulation etc

8. Nature of Disease: Transmission • Infective agents can be transmitted from one host to another by: • Direct contact • Droplets in air breathed or sneezed by host • Sexual contact (e.g. STIs) • Contaminated food or water • A carrying vector (e.g. rats carrying fleas) • An injecting vector (e.g. mosquitoes carrying malaria parasites) • Injection with infected needles and syringes

9. Non cellular pathogens: Viruses • A virus is a non-cellular agent composed of a protein coat (capsid) and nucleic acid (RNA OR DNA) • Rely on living cells to function and replicate: • Not able to respire • OBLIGATE intracellular parasites • Often integrated into host chromosomes and replicated during cell division • Highly specific to host cell or organism it infects (e.g. adenovirus specific to lung cells -> common cold) • All organisms on Earth are susceptible to virus infection (e.g. bacteriophages) • http://www.youtube.com/watch?v=Rpj0emEGShQ

10. Chicken pox

11. Shingles

12. Rubella or German measles

13. Mumps

14. Cold sore

15. Warts

16. Verruca

17. Polio

18. Small pox – a killer

19. Non cellular pathogens: Prions • Proteinaceaous infectious particles: NO GENOME • Deviant versions of a normal cell surface protein that are transmissable • Disease caused by accumulation of abnormal protease-resistant protein • Diseases include BSE (or mad cow), CJD, Kuru

20. Cellular pathogens: Bacteria • Prokaryotic organisms lacking organelles • Contain circular DNA molecule • Can be classified according to metabolic characteristics and/or shape Round Rod-shaped Spiral

21. Cellular pathogens: Bacteria • Cell wall contains PEPTIDOGLYCAN and is chemically and morphologically complex • Can have flagellum, capsules or spores • Reproduce rapidly by binary fission in favourable conditions • http://www.youtube.com/watch?v=gEwzDydciWc&NR=1

22. Eye infection

23. Leprosy

24. Tetanus

25. Plant blight

26. NOB Activity 7.1 & 7.2 • One group will set up activity 7.1 pg58-59 (procedure 1-5) • One group will set up activity 7.2 part A pg61-62 (procedure 1-8) • One group will set up activity 7.2 part B pg63 (procedure 1-6) • We will make observations next lesson

27. Homework – Chapter 7 • Quick check qu 1-25 • Biochallenge 1 • Chapter Review qu 2

28. Reflection • What did you learn about infection and disease today? • What was the most disgusting disease today?

29. Chapter 7: Infection and disease 2EL: To examine our bacteria investigations

30. Activity 7.1 & 7.2 Everyone will complete: • Activity 7.1 pg59, procedure 6-8, qu 1-7 • Activity 7.2 part A pg63, procedure 9, qu 1-8 • Activity 7.2 part B pg63, procedure 7, qu 10-15

31. Homework – chapter 7 • Quick check qu 26-30 • Biochallengequ 2 • Chapter review qu 4, 5, 6, 8

32. Reflection • Were you surprised by the results of any of the experiments and why?

33. Chapter 7: Infection and disease 3EL: To further explore the causes of disease

34. Expected learning • To further explore the causes of disease

35. Cellular pathogens: Fungi • Eukaryotic heterotrophs • break down organic matter by secreting enzymes and other chemicals • These chemicals are the main cause of the disease • Primarily terrestrial, but need moisture • Reproduce using spores • Cell wall made of chitin • Filamentous moulds and unicellular yeasts

36. Athletes foot

37. Oral Thrush

38. Frogs – chytrid fungus

39. Cellular pathogens: Protists • Unicellular eukaryotic organisms • Very diverse • Usually motile (i.e. flagella, cilia) • Heterotrophic • Reproduce sexually and asexually • May have specialist life cycle involving different hosts

40. Protist Life Cycle http://www.youtube.com/watch?v=Q_nCHDry0s8

41. Endoparasites: worms • Flat and round worms may be parasitic, but aren’t necessarily pathogenic • Pathogenic worms include tapeworms, roundworms

42. Endoparasites: worms

43. Ectoparasites: arthropods • Generally parasitic, but aren’t necessarily pathogenic • Pathogenic arthropods include head lice and body lice

44. Nelson Activity 5.2 • Complete activity 5.2 and hand in

45. Reflection • Why do you think parasites have evolved such a complex life cycle?