health and disease

• What are communicable diseases?


  Diseases that can be transferred from person to person or from one organism to another
• What are non-communicable diseases?


  Diseases that cannot be transferred from one organism to another
• How can different types of diseases interact?

  • Presence of one disease can increase the chance of developing another
  • Immune system defects increase susceptibility to diseases
  • Viruses can trigger cancer in living cells
  • Immune reactions can lead to allergic reaction, skin rashes and asthma
• What is a pathogen?


  An organism that causes a disease
• What are the four main types of pathogens?

  Viruses, bacteria, fungi and protists
• What is the life cycle of pathogens

  1. Infect a host
  2. Reproduce (or replicate for viruses)
  3. Spread though the body and infect other organisms
  4. Have structural adaptations for successful completion of their cycle
• What are diseases caused by pathogens considered communicable?


  Because they can be passed from one organism to another
• What are example of non-communicable diseases?

  1. Inherited genetic disorders (eg. cystic fibrosis)
  2. Deficiency diseases (due to lack of essential vitamins and minerals)
  3. Diseases like cancer (resulting from exposure)
• What are the way diseases can be transmitted?

  • Physical contact
  • Water
  • Air
  • Unhygienic food preparation
  • Vectors
• What is the life cycle of a virus similar to?

  Other pathogens
• How long can viruses usually survive outside a host?


  For long periods of time
• What happens when a virus infects a host cell?


  It replicates itself within the cells thousands of times
• What is the lytic pathway in the life cycle of a virus?

  • Viruses replicate their DNA and protien coats
  • New virus particals are assembled
  • Host cell bursts (lysis)
  • Nearby cells can then be infected
• What is the process called when a host cell bursts due to viral infection?

  Lysis
• What do phages do in the lysogenic pathway?


  They join their DNA to that of their host or leave small circles of DNA in the cytoplasm
• What happens to the viral DNA during the lysogenic pathway when host cells divide?



  The viral DNA is copied
• Why are viruses considered not alive?



  They don’t complete all 7 life processes
• What are the 7 life processes that viruses do not complete?



  Movement, respiration, sensitivity, nutrition, excretion, reproduction, and growth
• Can viral infections be treated with antibiotics?



  No, they cannot
• Are all bacteria pathogens that cause disease?



  No, many bacteria are useful
• What type of organisms are bacteria classified as?



  Prokaryotes
• How do bacteria differ from viruses in terms of structure?



  Bacteria are cells and larger, while viruses are not cells
• What is the main characteristic of protists?



  They are eukaryotic and have a nucleus
• What are the methods to prevent the spread of diseases?

  • Sterilizing water
  • Practicing hygiene (food and physical)
  • Vaccinations
  • Contraception