b6.3 - immune system

Question 1

ELISA test

Answer 1

sees if plant contains pathogen antigen

Question 2

ELISA test method

Answer 2

• obtain + liquidise sample put into a plastic tube
• wash to wash off any proteins not bound to plastic
• add a blocking agent to block all plastic that has not been covered with protein
• wash again to revive unbound blocking agent
• add antibody enzyme complex that is specific to pathogens antigen
• wash again to remove unbound antibody enzyme complex
• add colourless substrate that the enzyme changes into a coloured product
• if pathogen is present it’ll change colour

Question 3

primary immune defences

Answer 3

• skin
• mucous membranes
• blood clots
• respiratory surfaces

Question 4

skin

Answer 4

keratin layer , epidermis, sweat gland, hair follicle, dermis, subcutaneous layer
- waterproof barrier that prevents pathogens from entering

Question 5

commensalism bacteri

Answer 5

not harmful bacteria on the skin surface
- outcompete any pathogenic bacteria and fungi that may land on the skins surface

Question 6

mucous membranes

Answer 6

nasal muscles traps air borne organisms
any that get past get trapped in the respiratory tract
- mucus is produced by goblet cells
- and is removed by cilia beating passing it to stomach where high acidity denatures it
- contains LYSOZYME which is an antibiotic and destroys pathogens

Question 7

blood clots

Answer 7

• when skin is cute platelets are exposed to air
• cause a protein called FIBRINOGEN to change to fibrin (insoluble)
• fibrin forms a mesh over wound
• red blood cells are caught in the mesh - platelets stick together - form blood clots
• clot hardens to a scab keeping skin clean with time to heal

Question 8

respiratory surfaces

Answer 8

• mucus secreted by goblet cells trap dust particles and microbes
• cilia beat and waft the mucus up to the top of the throat when swallowed
• cilia contain many mitochondria to supply the energy needed

Question 9

types of white blood cells

Answer 9

• lymphocytes
• phagocytes

Question 10

lymphocytes

Answer 10

• produce antibodies that destroy pathogens - some provide immunity
• similar size to red blood cells with a spherical nucleus
• 25% of white blood cells

Question 11

phagocytes

Answer 11

• engulf bacteria and other microorganisms
  (phagocytosis)
• encloses bacteria in phagosome and digestive enzyme released to destroy bacteria
• relatively large cells, often with lobed nucleus (to allow it to engulf pathogens)
• ## 70% of white blood cells

Question 12

antigens

Answer 12

• protein on the cell membrane of pathogens
• each pathogen has uniquely shaped antigens
• some pathogens (eg flu) may alter antigens yearly

Question 13

antibodies

Answer 13

• are proteins made by lymphocytes
• have specific shape (3D) complementary to a specific antigen
• antibodies bind to antigens on the surface of pathogens

Question 14

how lymphocytes bind to antigens

Answer 14

• each lymphocyte has antibodies specific to antigens
• when an antigen is in the blood a lymphocyte with complementary receptor will be found and will bind to it
• the appropriate lymphocyte then divides by mitosis

Question 15

antibody structure

Answer 15

see diagram
- antigen binding site
- constant regions
- heavy chains
- light chains
- hinge
- variable parts ( change from antibody to antibody but dont change once its made)

Question 16

how antibodies kill pathogens

Answer 16

cell lysis
agglutination
neutralisation

Question 17

how antibodies kill pathogens - cell lysis

Answer 17

• may cause pathogens to burst open rendering them unable to infect our cells

Question 18

how antibodies kill pathogens - agglutination

Answer 18

• antibodies may bind to a number of pathogens causing them to clump together
• the group of pathogens is too large to enter a cell and can be destroyed by phagocytes

Question 19

how antibodies kill pathogens - neutralisation

Answer 19

• antibodies cover pathogens and prevent it from binding + entering a host
• antitoxins released from lymphocytes may also act on toxins released from pathogens rendering them ineffective

Question 20

monoclonal antibodies

Answer 20

are specific to one binding site on one antigen - target a specific cell/ chemical

Question 21

how many antibody types does a antigen make

Answer 21

one type of antibody specific to one antigen

Question 22

why are lymphocytes combined with other cells to make monoclonal antibodies

Answer 22

it cant divide anymore so if we want lots of antibodies we need a cells that will divide

Question 23

how to make monoclonal antibodies

Answer 23

• a mouse is infected with a specific antigen to stimulate lymphocytes to make particular antibodies
• extracted lymphocytes are combined with tumour cells that can divide and make antibodies (hybridoma cells)
• separated and each cell is cloned making cells that produce the same antibody
• antibodies are made, collected and purified

Question 24

monoclonal antibodies uses

Answer 24

• for diagnosis
• in research
• to treat some diseases

Question 25

monoclonal antibodies uses - for diagnosis

Answer 25

• pregnancy tests - monoclonal antibody binds to hCG in urine

Question 26

monoclonal antibodies uses - in research

Answer 26

• mAB can locate or identify specific molecules in a cell/tissue
• these have fluorescent tags in them
• the mABs then bind the specific molecules in the cell

Question 27

monoclonal antibodies uses - treat diseases

Answer 27

• for cancer mABs can be bound to a radioactive substance, a toxic drug/chemical- which stops cells growing or dividing
• it delivers the substance to cancer cells without harming healthy cells (specifically targeted)

Question 28

concerns with monoclonal antibody uses

Answer 28

• immunes responses occur as they come from mice cells with foreign proteins
• side effects - chills/fever, itchy rashes, nausea, headaches