Communicable diseases + immune response

• Communicable disease = a disease that can spread between organisms
• How is bacteria transported ?

  Through air, food, water or living vectors.
• How is tuberculosis spread?


  droplets in the air
• How do bacteria cause harm ?

  release toxins which damage tissue and host's cells
• Name example of bacteria infection in plants and animals ?

  tuberculosis

  ring rot
• What species does ring rot affect and what are the symptoms ?

  potatoes, tomatoes or aubergines

  damages leaves, tubers and fruit
• Describe the features of a virus ?

  non living

  no cellular structure

  made of genetic material wrapped in a protein
• How does a virus reproduce ?

  Inserts it's genetic material into host cell, host cell will then replicate virus.
• example of a virus ?

  HIV
• example of a virus in plants and its symptoms ?

  tobacco mosaic virus

  patterns of discolourisation on the leaves
• How are fungi transmitted ?

  direct contact
• How do fungi reproduce ?

  release a large number of spores
• example of fungi affecting plants and its symptoms ?

  black sigatoka in banana plants

  brown spots and streaks on leaves of trees
• example of fungi in humans and potential treatment ?

  athletes foot

  antifungal cream
• example of protoctista in plants and its symptoms ?

  potato blight, causes decay of the tublers
• example of protocista in humans and how is it transmitted ?

  malaria

  through vectors, mosquitos
• Name 7 non-specific defences in humans ?

  reflexes (coughing, sneezing )

  skin

  tears (contain lysozymes )

  cilia

  blood clotting

  inflammation

  phagocytosis
• How is the skin adapted to its function ?

  Provides a protective layer which is difficult for pathogens to penetrate

  Covered in harmless micro-organisms which reduce growth of pathogens by competing for resources
• Describe the process of blood clotting ?

  When platelets are exposed to external proteins they become activated

  Platelets form a plug over damaged area and release chemicals (clotting factors)

  This leads to eventually formation of fibrin which forms a mesh to trap the red blood cells + clot the blood.
• Describe what causes inflammation ?

  Damaged cells activate mast cells which release chemical, histamine.

  Histamine causes blood vessel walls to become more permeable and vasodilation, this results in more tissue fluid forming causing tissues to swell.
• What is the impact on pathogens of body temp increases ?

  reduces their ability to reproduce
• opsoin = recognise foreign chemicals and stick to them, tagging pathogens as foreign
• describe the process of phagocytosis for neutrophils ?

  Phagocytes attach to opsoin stuck to pathogenic antigen

  Phagocyte engulfs pathogen, forming a phagosome

  Lysosomes combine with phagosome forming a phagolysosome.

  Lysosomes enzymes break down + destroy pathogen.
• What is the difference between neutrophils and macrophages ?

  Macrophages have MHC which bind to pathogens antigen and the phagocyte presents them on its exterior to become a antigen presenting cells.
• What is the function of an antigen presenting cell ?

  present antigen to lymphocytes
• Name 3 functions of antibodies ?

  Neutralization of toxins and virus'

  Acting as opsoins

  Agglutination
• Link 3 structures of an antibody to its function ?

  Hinge region, flexible, allows distance between two antigens to vary

  Constant region, allows for the body to recognise it as self and for it to bind to phagocytes.

  Variable region, complementary to each antigen.
• Give an example of active natural immunity ?

  Immune response
• Give an example of natural passive immunity ?

  Receiving antibodies off mother through placenta or through colostrum.
• Give an example of artificial passive immunity ?

  Antibodies are injected, e.g tetnus
• Give an example of artificial active ?

  Vacines, antigen are injected into the body must still respond to produce antibodies and memory cells.
• epidemic = infectious disease spreads rapidly in a population (one country )
• pandemic = infectious disease spreads rapidly across several countries
• what is in vaccines?

  weakened or dead antigens
• What is the purpose of vaccines ?

  To stimulate primary immune response, leading to the production of memory cells for a quicker secondary response to the pathogen.
• Antigen variability = when a virus mutates an changes its surface antigens
• What was the first antibiotic ?

  penicilin
• What plant was aspirin discovered in ?

  willow tree
• What is the impact of antigen variability ?

  New vaccines need to be created and people must be re-vaccinated against new strain
• Pharmacogenetics = study of how a person's genetics affects their response to medical drugs