Bacteria and Viruses

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

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


  • Bacteria are prokaryotic with circular DNA; viruses have nucleic acid in a protein coat.
  • Bacteria do not require a host; viruses depend entirely on hosts.
  • Viruses are smaller than bacteria.
  • Bacteria have cell structures; viruses do not.
• What bacterium causes tuberculosis (TB)?

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

  The infection is symptomless as phagocytes are sealed in tubercles.
• What leads to the reactivation of tuberculosis bacteria?


  Weakening of the immune system
• What are the symptoms of active tuberculosis?


  Breathing problems, coughing, weight loss, and fever
• What virus causes AIDS?


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


  Fever, tiredness, and headaches
• What happens after HIV antibodies appear in the blood?


  The initial symptoms disappear until the immune system weakens again.