Communicable Diseases Prevention and the Immune System

• What are the main disease-causing pathogens in humans?

  Bacteria and viruses
• How do bacteria and viruses differ in terms of cellular structure?

  Bacteria are prokaryotic, viruses are not cells
• What form does bacterial genetic information take?

  Circular strand of DNA
• What is the composition of a virus?

  Nucleic acid enclosed in a protein coat
• How do the sizes of bacteria and viruses compare?

  Viruses are significantly smaller than bacteria
• Do bacteria require a host to survive?

  No, bacteria do not require a host
• What structures do bacteria possess that viruses do not?

  Bacteria have cell membrane, wall, and organelles
• What bacterium causes tuberculosis (TB)?

  Mycobacterium tuberculosis
• What happens during the first infection of TB?

  It is symptomless; phagocytes are sealed in tubercles
• Why do bacteria lie dormant in tubercles?

  They are not destroyed due to the waxy coat
• What symptoms arise when TB bacteria become active again?

  Breathing problems, coughing, weight loss, fever
• What is meningitis?

  Bacterial infection of the meninges
• What virus causes AIDS?

  Human Immunodeficiency Virus (HIV)
• What are the first symptoms of HIV?

  Fevers, tiredness, and headaches
• What is the result of a weakened immune system in HIV patients?

  It leads to AIDS
• What happens after several weeks of HIV infection?

  HIV antibodies appear in blood
• What does the influenza virus infect?

  Ciliated epithelial cells of the gas exchange system
• What is Athlete's foot caused by?

  A fungus
• How is Athlete's foot spread?

  Direct contact with spores
• What causes Malaria?

  Female Anopheles mosquito
• What is the tobacco mosaic virus?

  A virus that infects tobacco plants
• What are the physical barriers of plant defences against pathogens?

  Cellulose cell walls, lignin layer, waxy cuticles
• What happens when a pathogen is detected in plants?

  Mechanisms are activated to prevent infection spread
• What is necrosis in plants?

  Cells near infection are killed
• What is canker in plants?

  Necrosis of woody tissue
• What are menthols in plant chemical defences?

  Essential oils with antibacterial properties
• What do phenols like tannin do in plants?

  Interfere with digestion of insects
• What are defensins in plants?

  Cysteine-rich proteins inhibiting transport channels
• What is the role of lysozyme in animals?

  Kills bacterial cells by damaging cell walls
• What is the function of interferons?

  Prevent viruses from spreading to uninfected cells
• What is phagocytosis?

  Process where white blood cells engulf pathogens
• What happens after a pathogen is destroyed by phagocytosis?

  Antigens are presented on the phagocyte surface
• What are memory cells in the immune response?

  Cells that replicate when exposed to a pathogen

  
• What do B effector/plasma cells do?

  Produce antibodies

  
• What is the role of T helper cells?

  Stimulate B cells and T killer cells
• What is the function of T killer cells?

  Destroy pathogen-infected cells

  
• What are antibodies?

  Globular proteins produced by lymphocytes
• What is neutralisation in the context of antibodies?

  Inhibiting the action of a specific antigen
• What are the components of antibodies?

  Four polypeptide chains linked by disulphide bridges
• What is the constant region of an antibody?

  Region involved in phagocyte interaction