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Host and Defense > B cells: antibodies and diversity > Flashcards

B cells: antibodies and diversity Flashcards

1
Q

antibodies are??

A

targeted effector proteins

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2
Q

what are the three sources of antigen diversity?

A

genetic recombination
junctional diversity
somatic hypermutation

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3
Q

after negative and positive selection the B cells is considered

A

mature and leave the bone marrow and head to secondary lymphoid tissues

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4
Q

where do antibodies bind on antigens?

A

on the epitope of the antigen

1 antibody to 1 epitope

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5
Q

effector functions of antibodies

A

receptors in B cells and Granulocytes
neutralize
opsonize
signaling

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6
Q

the heavy chain determines what?

A

the isotype and thus the antibody class

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7
Q

what are the five antibody classes?

A 
IgA
IgG
IgM
IgD
IgE
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8
Q

the heavy chain has a proportionally small or large variable region?

A

small because there is no hypermutation that occurs here

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9
Q

what are the two isotypes of the small chains?

A

kappa and lambda

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10
Q

heavy chain characterisitics

A 
determines class
receptor interaction (Fc portion)
proportionally small variable region
binds antigen
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11
Q

light chain characteristics

A

binds antigen
proportionally large variable region
two isotypes

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12
Q

T/F each isotype can bind the same antigen and the same epitope

A

true because the variable region doesn’t change in class switching

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13
Q

what antibodies interact with j chians

A

IgM pentameric

IgA dimeric

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14
Q

what antibody is good at neutralization and diffusion and opsonization into extravascular tissues?

A

IgGs

also cross placenta

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15
Q

what antibody is good at activating the complement?

A

IgM (mostly in the blood) and IgG

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16
Q

what antibody sensitizes basophils

A

IgD

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17
Q

what antibody is good at transporting across epithelium?

A

IgA

18
Q

what antibody is good at sensitizing mast cells?

A

IgE

19
Q

antibody variable regions do what?

A

bind antigens

20
Q

antibodies can bind to what?

A

polysaccharides, globular proteins, lipids

21
Q

what is the difference between linear and discontinuous epitopes?

A

linear the recognition site is one after another

  • discontinuous the recognition sites are separated but due to structure are close
  • linear are used for antigen testing
22
Q

T/F antigens can different epitopes on their surface as well as repeated copies of epitopes on their surface?

A

true

23
Q

antibody structure facilitates what?

A

function

24
Q

what is the first antibody to be expression on a B cell?

A

IgM then an IgD

25
Q

Gene rearrangement occurs where?

A

bone marrow

*as well as junctional diversity

26
Q

once the B cell is in the secondary lymphoid tissue what happens?

A

somatic hypermutation and isotype switching

27
Q

what are the three portions of the variable region of the heavy chain?

A

variable
diversity
joining

28
Q

what are the two portions of the variable region of the light chain?

A

variable and joining

29
Q

T/F each loci for the light chain and heavy chain are located on different chromosomes?

A

true
kappa light is on chrom 2
lambda light is on chrom 22
heavy is on chrom 14

30
Q

what is the sequence of recombination?

A

the joining and diversity region are spliced together

  • the the DJ region is spliced to variable region
  • segments are randomly paired
31
Q

what does the RAG complex do?

A

randomly pairs gene segments

32
Q

order of pair gene segmentation

A
  1. Vh-Dh-Jh-> Vh-DJh
  2. Vh-DJh-> VDJh (heavy chain)
  3. VL-JL-> VJL
    * remember heavy chain is first
33
Q

what is junctional diversity?

2nd place of antibody diversity

A
  • *-when you are pairing a junctional with a diversity region you are adding nucleotides to the sequence and thus altering the DNA sequence thus changing protein structure
  • this occurs on light and heavy chains between the variable, diverse, and junction or joining regions
34
Q

Can a single B cell express all antibody isotypes?

A

yes

35
Q

is isotype switching permanent

A

yes with the acception of IgM and IgD

36
Q

why is isotype swithcing not permanent with IgM and IgD?

A

because the termination sequence is after the conserved regions of both IgM and IgD
-this means that at an mRNA step either IgM or IgD conserved regions are cut giving both IgM and IgD due to alternate splicing

37
Q

why are IgD important in B cell development?

A

they bind with Igalpha and Igbeta which allows for signaling

38
Q

upon antigen activation of the B cell what happens?

A

antibody secretion
somatic hypermutation and class switching
**only in mature B cells

39
Q

what are the three sources of antibody diversity?

A

Genetic recombination
Junctional diversity
Somatic hypermutation

40
Q

what does polyclonal mean?

A

multiple antibodies targeted against the same antigen

41
Q

what does monoclonal mean?

A

a single antibody targeted against a single antigen

42
Q

isotype switching occurs within the light or heavy chain?

A

heavy chain

remember the heavy chain determines isotype**

Host and Defense (26 decks)

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