[5.5] antibodies Flashcards

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1
Q

describe the structure of antibodies (draw and label a diagram)

A

shaped like a Y?

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2
Q

in what way does an antibody bind to an antigen?

A
  • forms an antigen-antibody complex
  • can hold multiple antigens at the same time
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3
Q

what are antigens made up of?

A
  • proteins
  • 4 polypeptide chains
  • therefore, they have a quaternary structure
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4
Q

what chains and bonds do antibodies have?

A
  • 2 light chains and 2 heavy chains
  • they are held together by strong covalent disulfide bonds
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5
Q

what are the constant and variable regions?

A
  • constant region is the part of each chain which will have exactly the same primary structure for all antibodies
  • variable region is the other part of each chain which will have a different specific sequence of amino acids for each specific antibody
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6
Q

what type of structure does the variable region have?

A

the variable regions each have a specific tertiary structure which form the 2 antigen binding sites

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7
Q

what is agglutination?

A
  • when antibodies bind to multiple antigens, therefore forming large clumps, which immobilises them
  • this makes it easier for phagocytes to destroy them through phagocytosis
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8
Q

how do you obtain monoclonal antibodies? [8]

A
  1. inject animal with antigen
  2. leave time for immune response
  3. harvest B cells from spleen
  4. fuse B cells with myeloma cells to form hydridomas
  5. grow hydridomas in petri dish - rapid mitosis due to high myeloma cell dvision rate
  6. test for production of desired antibody and isolate
  7. culture desired B cell
  8. harvest and purify antibodies

NB: ethical considerations?

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9
Q

why can MAbs be used in cancer treatment?

A
  • cancer tumour cells have specific antigens on their surface
  • specific complementary MAbs can bind to these antigens, destroying cancer cells by various means
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10
Q

how can MAbs be used in cancer treatment? (3)

A
  1. targeted delivery of anti-cancer drugs (indirect MAb therapy)
  2. signalling to cell -> apoptosis or prevention of cell cycle (direct MAb therapy)
  3. bringing macrophage / natural killer cell directly to the tumour
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11
Q

how can MAbs be used in pre-emptive treatment?

A

to give passive artificial immunity if potentially exposed to a new dangerous pathogen eg. rabies virus

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12
Q

what can monoclonal antibodies be used to diagnose?

A
  • influenza
  • hepatitis
  • chlamydia
  • cancers eg. prostate cancer
  • pregnancy
  • HIV
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13
Q

how are monoclonal antibodies utilised in pregnancy tests?

A
  • the placenta produces a hormone called hCG, which can be found in the mother’s urine
  • MAbs present on the test strip are linked to coloured particles
  • if hCG is present in the urine it binds to these antibodies
  • the hCG-antibody-colour complex moves along the strip until it is trapped by a different type of antibody creating a coloured line
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14
Q

ethical issues of monoclonal antibodies

A
  • production of MAbs involves deliberately inducing cancer in mice
  • there have been some deaths associated with their use in the treatment of multiple sclerosis
  • in march 2006, six healthy volunteers took part in a trial of a new MAb. within minutes, they suffered multiple organ failure
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