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BIOLOGY UNIT 3

BIOLOGY UNIT 3. What is a disease?. Any condition that interferes with how an organism, or any part of it, functions. Diseases are described as endemic if they are common in a population but at a low level.

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BIOLOGY UNIT 3

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  1. BIOLOGY UNIT 3

  2. What is a disease? • Any condition that interferes with how an organism, or any part of it, functions. • Diseases are described as endemic if they are common in a population but at a low level. • If there is a sudden increase in the incidence of the disease in the population of a species, it is referred to as an outbreak. • Sometimes, outbreaks of disease spread rapidly across the world and these are referred to as pandemics. 12 BIOLOGY, CH 5

  3. What is a disease? • Infectious diseases (eg. tuberculosis) are caused by an agent that can be transmitted from one organism to another. • Contagious infection transmitted by direct contact. • Non-infectious diseases cannot be transmitted directly from one person to another. SRAM 2012: 114,115 12 BIOLOGY, CH 5

  4. Common Diseases 12 BIOLOGY, CH 5

  5. Review questions – set 1 12 BIOLOGY, CH 5

  6. The Nature of Disease • Pathogens differ in their disease-causing capacity or pathogenicity. • The intensity of the effect of the pathogen is called its virulence. • Individuals vary in their susceptibility to a pathogen – some have greater resistance than others. 12 BIOLOGY, CH 5

  7. The Nature of Disease 12 BIOLOGY, CH 5

  8. Review questions – set 2 12 BIOLOGY, CH 5

  9. Non-cellular Agents as Pathogens Viruses Virioids Prions 12 BIOLOGY, CH 5

  10. Viruses Viruses - composed of a proteincoat and nucleicacid, either DNA or RNA but never both. They have no metabolic machinery for processes such as cellular respiration. They rely totally on the host cell to provide them with materials for their reproduction. Mythconceptions – viruses worksheet 12 BIOLOGY, CH 5

  11. Viruses SRAM 2012: 124 12 BIOLOGY, CH 5

  12. Virus Replication 12 BIOLOGY, CH 5 SRAM 2012: 127

  13. Avian Flu Virus 12 BIOLOGY, CH 5 (from Jacaranda Biology 3&4)

  14. Viral Diseases 12 BIOLOGY, CH 5 SRAM 2012: 131-2

  15. 12 BIOLOGY, CH 5 Nelson Text: 146

  16. Viroids Viroids are small infectious particles that consist of a single circular RNA molecule. They lack the protein envelope found in viruses and do not produce any protein products. Viroids infect plants, but not animals. 12 BIOLOGY, CH 5

  17. Prions (pree-ons) small infectious proteins transmissible spongiform encephalopathy (TSE) is fatal by causing degeneration of the nervous system. the brains of infected victims have a spongy appearance due to large, intracellular vacuoles. The most notorious TSE of late is mad cowdisease (bovine spongiform encephalopathy) 12 BIOLOGY, CH 5

  18. Prions (pree-ons) Human TSE, variant Creutzfeldt-Jakob disease (CJD), is characterised by gradual loss of motor coordination, dementia and paralysis, eventually leading to death. Prions are unique among pathogenic agents as they do not possess any genetic material, neither DNA nor RNA. 12 BIOLOGY, CH 5

  19. Prions (pree-ons) Prion proteins exist in our bodies normally and play important roles in memory, learning and passing signals from cell to cell. They exist in two forms: the normal PrPc form and the disease-causing PrPSc form. When a PrPSc molecule encounters an unaltered PrPc form, it converts it to the harmful form, which in turn converts others. The PrPSc forms aggregate to form long filaments that gradually damage neural tissue. 12 BIOLOGY, CH 5

  20. Prions A computer-generated image of the human prion protein. A normal prion PrPc Disease-causing prion PrPSc 12 BIOLOGY, CH 5

  21. Prions – Mad Cow Disease (from Jacaranda Biology 3&4) SRAM 2012: 133 12 BIOLOGY, CH 5

  22. Prions – Mad Cow Disease 12 BIOLOGY, CH 5

  23. Review questions – set 3 12 BIOLOGY, CH 5

  24. Cellular Agents as Pathogens • Bacteria • Fungi • Protists • Multicellular parasites • Endoparasites • Ectoparasites 12 BIOLOGY, CH 5

  25. Bacterial Structure 12 BIOLOGY, CH 5

  26. Bacterial classification 12 BIOLOGY, CH 5

  27. Bacterial classification 12 BIOLOGY, CH 5

  28. Bacterial reproduction BINARY FISSION! 12 BIOLOGY, CH 5

  29. Bacterial reproduction 12 BIOLOGY, CH 5

  30. Bacteria Do SRAMs on Bacteria and Antimicrobial Chemicals (from Jacaranda Biology 3&4) SRAM 2012: 137-8, 141 E.coli in penicillin Staph & MRSA 12 BIOLOGY, CH 5

  31. 12 BIOLOGY, CH 5 Nelson Text: 150

  32. 12 BIOLOGY, CH 5 Nelson Text: 152

  33. Bacteria 12 BIOLOGY, CH 5

  34. Fungi (from Jacaranda Biology 3&4) 12 BIOLOGY, CH 5

  35. Fungi 12 BIOLOGY, CH 5

  36. Review questions – set 4 12 BIOLOGY, CH 5

  37. Protists Unicellular eukaryotes. They reproduce both sexually and asexually. We do not have effective vaccines and chemicals against them. 12 BIOLOGY, CH 5

  38. Protists • Giardia lamblia. • flagellated protozoan • Causes mild intestinal upsets • Normally found in cattle and wild animals • Forms cysts in the faeces 12 BIOLOGY, CH 5

  39. Protists • Trypanosoma brucei • flagellated protozoan • Causes African sleeping sickness • Fatal when it reaches the brain • Life cycle involves different hosts 12 BIOLOGY, CH 5

  40. PLASMODIUM and the ANOPHELES mosquito: • Malaria is caused by the small protozoan, Plasmodium. • Humans (or other hosts) become infected when bitten by a female Anopheles mosquito. Protists SRAM 2012: 123 12 BIOLOGY, CH 5

  41. Review questions – set 5 12 BIOLOGY, CH 5

  42. Endoparasites Life cycle of the blood fluke, Schistosoma japonicum, which causes schistosomiasis. 12 BIOLOGY, CH 5

  43. Endoparasites 12 BIOLOGY, CH 5

  44. Ectoparasites Mostly arthropods: fleas, ticks, etc. Do not cause very serious diseases. Usually are vectors for endoparasites. 12 BIOLOGY, CH 5

  45. Review questions – set 6 12 BIOLOGY, CH 5

  46. Keeping Pathogens out First Line of Defence (Innate): 12 BIOLOGY, CH 5

  47. Review questions – set 7 12 BIOLOGY, CH 5

  48. Keeping Pathogens out First Line of Defence (Innate): 12 BIOLOGY, CH 5

  49. Plant Defence Strategies Thick waxy cuticle (list others as an answer to question 25 review set 8) PLANT DISEASES: SRAM 2012: 142 12 BIOLOGY, CH 5

  50. Review questions – set 8 12 BIOLOGY, CH 5

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