Communicable diseases, prevention and the immune system

• Name four groups of pathogens that can cause communicable diseases.

  Bacteria, fungi, protoctista, viruses
• How does Mycobacterium tuberculosis cause disease?

  It triggers an inflammatory response by infecting phagocytes in the lungs.
• What happens to infected phagocytes in Mycobacterium tuberculosis infection?

  They are sealed in waxy-coated tubercles, allowing the bacteria to remain dormant.
• What occurs if another factor weakens the immune system in a Mycobacterium tuberculosis infection?

  The bacteria become active and destroy lung tissue.
• How does HIV result in the symptoms of AIDS?

  HIV binds to CD4 receptors on TH cells, replicates inside them, and eventually leads to their destruction.
• What happens when there are too few TH cells in the body due to HIV?

  AIDS develops, and the immune system cannot function properly.
• What are the consequences of AIDS on an individual's health?

  Individuals cannot destroy other pathogens and suffer from secondary diseases or infections.
• How does the tobacco mosaic virus cause disease in plants?

  It is mainly transmitted via infected sap and causes stunted growth and mottled leaves.
• What is the mechanism of the tobacco mosaic virus in host cells?

  It contains ssRNA, which is transcribed by the host cell to assemble new virions.
• How does the influenza virus cause disease?

  It is transmitted via droplet infection, contact with mucus, zoonotic infection, and contact with fomites.
• What happens when the influenza virus injects its RNA into host cells?

  The viral RNA hijacks the cell's biochemistry to produce new virions, leading to cell lysis.