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Topic 6Infection, Immunity and ForensicsRevision<br />
Microorganisms<br />What is a Pathogen?<br />Microorganisms that causes disease<br />There are five main groups of pathoge...
Virus<br />Smallest of all living organisms<br />Size<br />0.02 to 0.3 micrometer<br /> Viruses are not cells.<br />Becaus...
Obligate parasite<br />Viruses are obligate parasites because they cannot reproduce and increase in number without a host....
Structure of virus<br />Nucleic acid core (DNA or RNA) + protein coat (capsid)<br />Capsid is made of protein subunits cal...
TMV<br />Tobacco Mosaic Virus<br />Leaf infected with TMV<br />
Retroviruses<br />Viruses with RNA as their genetic material.<br />
HIV - Replication<br />HIV attaches to the surface of macrophage (host cell)<br />gp120 protein (virus surface) + CD4 prot...
HIV - Replication<br />Using the host cell machinery, mRNA is synthesized from the new proviral DNA<br />Viral mRNA is tra...
HIV - Replication<br />Eventually the gene that code for gp120 protein is mutated.<br />The new protein attaches to a diff...
HIV - Transmission<br />Through sexual contact<br />Through infected blood<br />by intravenous drug users sharing needles<...
AIDS - Symptoms<br />fever<br />persistent diarrhoea<br />weight loss<br />secondary infections such as TB, pneumonia, Kap...
AIDS - Prevention<br />Practicing monogamy<br />Use of condoms<br />Use of clean needles<br />Awareness programmes<br />
Why is it difficult to create a vaccine for AIDS?<br />The virus mutates rapidly<br />Therefore the antigens on the viral ...
Bacteria<br />Bacterial cells are about 10 times smaller than eukaryotic cells and are typically 0.5–5.0 micrometers in le...
Structure of Bacteria<br />Ribosomes. <br />Same function as eukaryotic cells (protein synthesis), but are smaller (70s ra...
Structure of Bacteria<br />Plasmid. <br />Very small circles of DNA, containing non-essential genes. <br />Can be exchange...
Structure of Bacteria<br />Mesosome. <br />Tightly-folded region of the cell membrane containing all the proteins required...
Structure of Bacteria<br />Gram positive bacteria <br />have a thick cell wall and stain purple<br />Gram negative bacteri...
Gram Stain<br />Gram stain is used to colour the bacterial cell wall for identification.<br />Teichoic acid present in the...
Structure of Bacteria<br />Capsule (Slime Layer). <br />Thick polysaccharide layer outside of the cell wall. <br />Used fo...
Pathogenic bacteria<br />Cause infectious diseases, including <br />Cholera<br />Tuberculosis<br />Anthrax<br />Bubonic pl...
Toxins produced by bacteria<br />Endotoxins<br />Lipopolysaccharides which are part of the outer layer of gram negative ba...
Toxins produced by bacteria<br />Exotoxins<br />Proteins produced and released into the body by bacteria which causes seve...
Bacterial reproduction<br />Binary fission<br />Replication of DNA<br />Replication of plasmids<br />Cytoplasm and cell wa...
Bacterial reproduction<br />Transformation<br />Many bacteria can acquire new genes by taking up DNA molecules from their ...
Nuclear envelope<br />Glycogen<br />Lipids<br />Plasmids<br />Flagellum<br />
Flagellum<br />DNA<br />
Glycogen<br /><ul><li>Made of {peptidoglycan / murein}
does not contain cellulose</li></li></ul><li>
Lungs<br />They {are immune / are resistant / have been vaccinated / have had BCG};<br />Have antibodies / have memory cel...
Prolonged drug treatment (3-9 months) / eq;<br />Antibiotics / isoniazid / eq;<br />At least 3 (antibiotics) are used / eq...
Tuberculosis<br />TB is caused by the bacterium <br />Mycobacterium tuberculosis<br />
Tuberculosis<br />Symptoms<br />Coughing up blood in sputum<br />Weakness<br />Damage to the lung tissue<br />Suppression ...
Tuberculosis<br />Tubercle<br />Mass of tissue formed in the lung as a result of inflammatory response to infection by the...
Infection occurs through inhaling contaminated air or drinking infected milk.<br />Primary infection - early stage of infe...
Diagnosis of TB<br />X-rays<br />Sputum testing for bacteria<br />
Treatments<br />Antibiotics are used for many months.<br />A cocktail of different antibiotics are used.<br />
Prevention<br />BCG (Bacillus Calmette Guerin)<br />Improving living standards<br />Treating diseases in cattle<br />Prote...
Topic 6 infection, immunity and forensics revision
Topic 6 infection, immunity and forensics revision
Topic 6 infection, immunity and forensics revision
Topic 6 infection, immunity and forensics revision
Topic 6 infection, immunity and forensics revision
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Topic 6 infection, immunity and forensics revision

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Topic 6 infection, immunity and forensics revision

  1. 1. Topic 6Infection, Immunity and ForensicsRevision<br />
  2. 2. Microorganisms<br />What is a Pathogen?<br />Microorganisms that causes disease<br />There are five main groups of pathogens<br />bacteria<br />Viruses<br />Fungi<br />protista <br />worms<br />
  3. 3. Virus<br />Smallest of all living organisms<br />Size<br />0.02 to 0.3 micrometer<br /> Viruses are not cells.<br />Because they lack all cell organelles and cytoplasm.<br />But they can invade other cells and take over their biochemistry to make more viruses.<br />This is why they are still studied as living organisms.<br />
  4. 4. Obligate parasite<br />Viruses are obligate parasites because they cannot reproduce and increase in number without a host.<br />Facultative parasites<br />Organisms that live as parasites only when a host is available or else they maintain a free living lifestyle<br />
  5. 5. Structure of virus<br />Nucleic acid core (DNA or RNA) + protein coat (capsid)<br />Capsid is made of protein subunits called capsomeres .<br />Some viruses have lipid rich covering around capsid called the envelope.<br />Envelope usually is formed from host cell membrane.<br />Envelope may have spikes to help chemically recognize & attach to the host cell.<br />
  6. 6. TMV<br />Tobacco Mosaic Virus<br />Leaf infected with TMV<br />
  7. 7. Retroviruses<br />Viruses with RNA as their genetic material.<br />
  8. 8. HIV - Replication<br />HIV attaches to the surface of macrophage (host cell)<br />gp120 protein (virus surface) + CD4 protein (host cell membrane)<br />Reverse transcriptase makes a DNA copy of the viral RNA.<br />DNA copy is replicated by the same enzyme.<br />This new DNA moves into the nucleus and integrated into the host cell chromosome.<br />
  9. 9. HIV - Replication<br />Using the host cell machinery, mRNA is synthesized from the new proviral DNA<br />Viral mRNA is translated to make viral enzymes and structural proteins.<br />Viral RNA genome is also made from the proviral DNA.<br />The viral genome and structural proteins assemble to form the basic structure of the virus.<br />These move out of the host cell by exocytosis, taking part of the cell membrane with it (lipid layer around the virus).<br />
  10. 10. HIV - Replication<br />Eventually the gene that code for gp120 protein is mutated.<br />The new protein attaches to a different CD4 protein present in T cells.<br />The same cycle repeats in T cells.<br />But as the virus leave the T cell, it destroys the cell membrane killing the host cell.<br />This reduces the number of T cells in the body reducing immunity.<br />
  11. 11. HIV - Transmission<br />Through sexual contact<br />Through infected blood<br />by intravenous drug users sharing needles<br />repeated use of needles<br />use of infected blood products<br />from mother to foetus<br />during early stages of pregnancy<br />during birth<br />through breastfeeding<br />
  12. 12. AIDS - Symptoms<br />fever<br />persistent diarrhoea<br />weight loss<br />secondary infections such as TB, pneumonia, Kaposi's sarcoma<br />
  13. 13. AIDS - Prevention<br />Practicing monogamy<br />Use of condoms<br />Use of clean needles<br />Awareness programmes<br />
  14. 14. Why is it difficult to create a vaccine for AIDS?<br />The virus mutates rapidly<br />Therefore the antigens on the viral surface continuously changes<br />Working on animals to develop vaccines is not possible because HIV infects only humans<br />The virus hides itself for years inside macrophages, therefore most vaccines may not work properly<br />
  15. 15. Bacteria<br />Bacterial cells are about 10 times smaller than eukaryotic cells and are typically 0.5–5.0 micrometers in length. <br />Bacteria are vital in recycling nutrients, and many important steps in nutrient cycles depend on bacteria, such as the fixation of nitrogen from the atmosphere.<br />Large numbers of useful bacteria are found on the skin and in the digestive tract of humans and other animals.<br />
  16. 16. Structure of Bacteria<br />Ribosomes. <br />Same function as eukaryotic cells (protein synthesis), but are smaller (70s rather than 80s). <br />DNA. <br />Always circular, and not in chromosome form.<br />Naked (Histones are absent).<br />Attached to cell membrane at least at one point.<br />
  17. 17. Structure of Bacteria<br />Plasmid. <br />Very small circles of DNA, containing non-essential genes. <br />Can be exchanged between different bacterial cells.<br />Cell membrane. <br />made of phospholipids and proteins, like eukaryotic membranes. <br />
  18. 18. Structure of Bacteria<br />Mesosome. <br />Tightly-folded region of the cell membrane containing all the proteins required for respiration and photosynthesis. <br />Cell Wall. <br />DIFFERENT from plant cell wall. <br />Made of murein (a protein) {Peptidoglycan}<br />There are two kinds of cell wall, which can be distinguished by a Gram stain: <br />
  19. 19. Structure of Bacteria<br />Gram positive bacteria <br />have a thick cell wall and stain purple<br />Gram negative bacteria <br />have a thin cell wall with an outer lipid layer and stain pink.<br />
  20. 20. Gram Stain<br />Gram stain is used to colour the bacterial cell wall for identification.<br />Teichoic acid present in the cell wall of gram positive bacteria bind to crystal violet in the gram stain to give the cell wall a purplecolour.<br />Gram negative bacteria don't have teichoic acid, and the crystal violent is decolourised and are replaced by red safranine in the gram stain, so the wall appears pink.<br />
  21. 21. Structure of Bacteria<br />Capsule (Slime Layer). <br />Thick polysaccharide layer outside of the cell wall. <br />Used for:<br />Sticking cells together<br />As a food reserve<br />As protection against desiccation (drying out) and chemicals, and <br />as protection against phagocytosis (being broken down by a white blood cell). <br />
  22. 22. Pathogenic bacteria<br />Cause infectious diseases, including <br />Cholera<br />Tuberculosis<br />Anthrax<br />Bubonic plague<br />
  23. 23. Toxins produced by bacteria<br />Endotoxins<br />Lipopolysaccharides which are part of the outer layer of gram negative bacteria which cause symptoms of disease.<br />cause fever, vomiting and diarrhoea <br />examples: endotoxins from Salmonella, E. coli<br />
  24. 24. Toxins produced by bacteria<br />Exotoxins<br />Proteins produced and released into the body by bacteria which causes severe symptoms of disease.<br />These soluble proteins cause damage to cell membranes, internal bleeding, affect neurotransmitters, and poison cells.<br />Example: botulinum toxin produced from Clostridium botulinum.<br />
  25. 25. Bacterial reproduction<br />Binary fission<br />Replication of DNA<br />Replication of plasmids<br />Cytoplasm and cell wall splits into two<br />Generation time<br />The time between divisions of bacteria.<br />
  26. 26. Bacterial reproduction<br />Transformation<br />Many bacteria can acquire new genes by taking up DNA molecules from their surroundings.<br />Transduction<br />Transduction is the process by which bacterial DNA is moved from one bacterium to another by a virus.<br />Conjugation<br />Some bacteria can transfer a portion of their chromosome to a recipient bacteria.<br />
  27. 27. Nuclear envelope<br />Glycogen<br />Lipids<br />Plasmids<br />Flagellum<br />
  28. 28. Flagellum<br />DNA<br />
  29. 29. Glycogen<br /><ul><li>Made of {peptidoglycan / murein}
  30. 30. does not contain cellulose</li></li></ul><li>
  31. 31.
  32. 32. Lungs<br />They {are immune / are resistant / have been vaccinated / have had BCG};<br />Have antibodies / have memory cells;<br />3. Bacteria destroyed before they cause damage / eq.<br />
  33. 33. Prolonged drug treatment (3-9 months) / eq;<br />Antibiotics / isoniazid / eq;<br />At least 3 (antibiotics) are used / eq;<br />Rest / healthy diet / direct observation therapy;<br />
  34. 34. Tuberculosis<br />TB is caused by the bacterium <br />Mycobacterium tuberculosis<br />
  35. 35. Tuberculosis<br />Symptoms<br />Coughing up blood in sputum<br />Weakness<br />Damage to the lung tissue<br />Suppression of immunity<br />Loss of appetite<br />Loss of weight<br />Night sweats and fever<br />
  36. 36. Tuberculosis<br />Tubercle<br />Mass of tissue formed in the lung as a result of inflammatory response to infection by the TB bacterium.<br />
  37. 37. Infection occurs through inhaling contaminated air or drinking infected milk.<br />Primary infection - early stage of infection.<br />Development of tubercle<br />Bacteria are destroyed by WBC and the tissue heals.<br />Some bacteria produce thick waxy layer around them and survive.<br />When the person's immune system is weakened these bacteria become active and divide.<br />This leads to active TB.<br />
  38. 38. Diagnosis of TB<br />X-rays<br />Sputum testing for bacteria<br />
  39. 39. Treatments<br />Antibiotics are used for many months.<br />A cocktail of different antibiotics are used.<br />
  40. 40. Prevention<br />BCG (Bacillus Calmette Guerin)<br />Improving living standards<br />Treating diseases in cattle<br />Protected clothing when contacting people with TB<br />

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