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604 EX 1 > 1.4 antibody diversity > Flashcards

1.4 antibody diversity Flashcards

1
Q

how does B cell produce antibodies?

A
  • B cell encounteres and binds antigen
  • stimulated B cell gives rise to plasma cell
  • plasma cell makes antibodies
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2
Q

what is an antibody made up of?

A
  • N terminus and C terminus (n binds antigen)
  • light chain
  • heavy chain
  • hinge region
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3
Q

what does hinge region allow?

A

antibody to bind to unique epitope on each side ( antibody can bend and reognize epitopes not in the same place)

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4
Q

IgG can be cleaved by ______ and that leaves 2Fab and 1 FC (tail)

A

papain

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5
Q

Fab can be used in ______

A

diagnostic testing

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6
Q

there are ___ types of heavy chains and ____ types of light chain that make up 5 immunoglobulin classes

A

5,2

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7
Q

if you grab an antibody thats coiled up and straighten it out, you would see the _____

A

hypervariable regions

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8
Q

the hyper-variable regions are where?

A

at the tip/the antigen binding site

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9
Q

the variability of the binding site allows the antibody to ________

A

recognize a certain type of foreign molecule

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10
Q

bonding between Ab chains and an antigen are _____

A

non-covalent

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11
Q

multivalent antigens can have ______ or ______

A

different epitopes or a repeated epitope

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12
Q

epitopes can be_______ or _____

A

linear (Amino acids right after another)

discontinuous (amino acids from different sections, if you denature the antigen you denature the stimuation)

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13
Q

what causes the antibody diversity in the genomic structure?

A

the variable diversity joining

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14
Q

somatic recombination happens during the _____

A

maturation process of B cells

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15
Q

a random V + random J + random D = random VDJ joint and the information inbetween them is ____-

A

cut out

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16
Q

12/23 rule

A

prevents rearrangement of V or J genes within their own clusters and ensures the obligatory inclusion of a D segment in heavy chain genes

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17
Q

How does recombination happen?

A
  • 2 RAG molecules bind (one recognizes 12, one recognizes 23)
  • two RAGs come together and detach/float away
  • the V/J are joined together
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18
Q

light chain vs heavy chain somatic recombination?

A

light chain: V+J join and inner info is cut out

heavy chain: D+J join, info is excised, then DJ join V

19
Q

Junctional diversity

A

how sides join after RAGs cut off and float away

20
Q

steps of junctional diversity?

A
  1. heptamers are clipped
  2. hair pin forms bw 2x2 nucleotides and swings it out to be a 4x1
  3. TdT adds nucleotides randomly until it finds a homology, trims the end, and then the joints are filled in
21
Q

what is TdT

A

terminal di-oxy transferase

adds nucleotides to ends of palindromic strands

22
Q

B cell early life steps

A
  1. each B cell undergoes somatic recombination
  2. unique VDJ = unique junctional diversity
  3. this encodes a unique binding site
    4, we may/may not be able to transcribe this whole thing due to combination of nucleotides
  4. we must be able to transcribe/translate this whole thing
23
Q

there is strong ______ in B lymphocytes

A

allelic exclusion ( allows each mature B lymphocyte to only express one type of immunoglobulin)

24
Q

there are always _____ next to B cell receptors, they just arent drawn all the time

A

IgB, Iga

25
Q

IgM and IgD can be transcribed at the same time on ______

A

NAIVE B-cells (mature but havent been stimulated by antigen)

  • transcribes from VDJ, mu, delta
  • this undergoes through differential RNA splicing
  • fxnl VDJ expression = IgM and IgD expressed at same time & expressed on naive B cells (signal that cell is mature)
26
Q

what is a signal that a B-cell is mature?

A

IgM and IgD co-expression

27
Q

now that the B-cell has Igm and IgD, it can ______

A

leave bone marrow and look for antigen

28
Q

once IgM is stimulated, it switches from ________ to a _____. and this is done by _______

A

transmembrane B cell receptor
secreted IgM molecule
differential RNA splicing

29
Q

when IgM is stimulated it no longer has _____

A

C-terminus for transmembrane IgM (bc its secreted)

30
Q

the affinity of an antibody molecule ______ for antigen after stimulation because VDJ is subjected to hypermutation. What can this produce?

A

INCREASES

- a mol that binds better

31
Q

after immunization, what happens in the next 2 weeks with hypermutations?

A
  • as time goes along, AID subjects hyper-variable region to new hypermutations which makes new antibody molecules
  • these molecules are selected based upon their affinity for the antigen
  • the highest affinity is stimulated first
32
Q

secreted IgM is usually seen as a _______

A

pentamer

33
Q

class switching requires ______

A

recombination

34
Q

AID plays a role in recombination and puts a clip on two sections, then what happens?

A
  • DNA between these clips are looped out
  • this loop is cut out and floats away
  • transcription happens to whatever is left
35
Q

IgG1 has very strong _____

A

secondary response

36
Q

IgG4 has very long_____

A

1/2 life

37
Q

IgA is the only one that crosses ______

A

epithelium

38
Q

ALL IgG does _____, while only some IgG do _____

A

neutralization, opsonization

39
Q

IgM activates the _____

A

complement system (C1)

40
Q

IgG is the only one that can cross _____

A

placenta

41
Q

IgD doesnt do anything except _____

A

go on surface of naive, but mature B cell, because co-transcription

42
Q

IgA exists as a ____ on the mucosal surface, and binds and neutralizes things

A

dimer

43
Q

what are the irreversible changes to B cell genome?

A
  • v-region assembly
  • junctional diversity
  • assembly of transcriptional controlling elements
  • somatic hypermutation
  • class switching of genomic DNA
44
Q

what are the reversible/regulated changes in immunoglobulin genes during a B cells life?

A
  • transcription activated with co-expression of IgM/IgD

- synthesis changes from membrane Ig to secreted antibody

604 EX 1 (5 decks)

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