pathogens

• pathogens are microbes that cause disease- bacteria, viruses, protoctist , fungi
• bacteria


  -producing toxins/ waste products

  -damage cells (rare)

  -in plants- cause death of vascular tissues- phloem and xylem

  -tuberculosis, bacterial meningitis, ringrot
• viruses

  -genetic material surrounded by a protein coat called a caspid

  -variety of shapes and very small

  -invade host cells and insert genetic material into the hosts DNA

  -cells manufacture more copies of the virus- burst out of the cell and cause damage- physical damage- makes you ill

  -HIV, tobacco mosaic virus, influenza
• fungi


  animals- microsporum species in skin- send out reproductive hyphae- grow to surface of skin and release spores

  -plants- live in vascular tissue and hyphae releases extracellular enzymes which digest the surrounding tissues and cause decay

  -athlete's foot, black sigatoka (bananas)
• protoctists


  -eukaryotic single-celled (mostly) organism that form a diverse group

  -similar features to animal cells

  -malaria, tomato/ potato late blight