4.1.7 antibodies Flashcards

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1
Q

agglutins

A

antibodies that cause pathogens to stick together

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2
Q

anti-toxins

A

antibodies that render toxins harmless

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3
Q

opsonins

A

antibodies that make it easier for phagocytes to engulf the pathogen

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4
Q

primary immune response

A

initial response caused by 1st infection

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5
Q

secondary immune response

A

more rapid & vigorous response caused by 2nd or subsequent infection caused by same pathogen

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6
Q

what are antigens

A

a molecule that can stimulate an immune response

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7
Q

what molecules are usually antigens

A

(almost any molecule could be an antigen)
they’re usually proteins/glycoproteins in plasma membrane of pathogen

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8
Q

what are antibodies specific to

A

the antigen

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9
Q

antibodies are..

A

immunoglobins

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10
Q

what are immunoglobins

A

complex proteins produced by plasma cells in the immune system

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11
Q

when are immunoglobins released

A

in response to an infection

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12
Q

structure of an antibody

A
  • y-shaped
  • 4 polypeptide chains
  • disulfide bridges hold polypeptides together
  • hinge region = allow flexibility to allow molecule to grip 1+ antigen
  • 2 distinct regions:
    1. variable region = shape specific to antigen
    2. constant region = same in all antibodies –> may have site for easy binding of phagocytic cells
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13
Q

3 main groups of antibodies

A
  1. opsonins
  2. agglutins
    3 anti-toxins
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14
Q

how do opsonins work & what are they

A
  • group of antibodies which bind to the antigens on a pathogen
  • then act as binding sites for phagocytic cells
  • some aren’t very specific & stick to types of molecules that are not found in the host cell
  • others are produced as part of the specific immune response & bind to very specific antigens
  • assists in phagocytosis but prevents the pathogen entering a host cell before it can be attacked by phagocytes
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15
Q

what’s neutralisation

A
  • the pathogen may have another use for the antigen molecule
  • eg. it may be a binding site used for attachment to the host cell
  • the opsonin bound to the antigen renders it useless
    = neutralisation
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16
Q

how do agglutins work & what are the 2 advantages

A
  • as each antibody molecule has 2 identical binding sites, it is able to ‘cross-link’ pathogens by binding an antigen on 1 pathogen with 1 binding site & then an antigen from another pathogen with its other binding site
  • when many antibodies perform this cross-linking they clump together (agglutinate) pathogens
  • particularly effective against viruses

2 advantages
- agglutinated pathogens are physically impeded form carrying out some functions eg. entering host cells
- agglutinated pathogens are readily engulfed by phagocytes

17
Q

how do anti-toxins work

A

some antibodies bind to molecules that are released by pathogenic cells
–> these molecules may be toxic & anti-toxins render them harmless

18
Q

what’s the primary immune response

A
  • immune system produces antibodies once infecting agent is detected
  • few days before no. of antibodies in blood rises to level that’s able to combat infection effectively
19
Q

what’s the secondary immune response

A
  • antibodies don’t stay in blood

however, if body is re-infected:
- B/T memory cells circulating in blood due to specific immune response
- recognise specific antigens & immune system can start quicker
- production of antibodies starts sooner/is more rapid
- conc. of antibodies rises sooner & reaches higher conc.