Antibody and antigen Flashcards

1
Q

What is a B-cell receptor

A

Membrane bound Ig on the B-cell surface

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2
Q

What is an antibody

A

Secreted Ig of the same antigen specificity as the BCR

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3
Q

What are antigens

A

foreign and endogenous substances recognized by the immune system

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4
Q

what is an immunogen

A

antigen that induces an immune response

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5
Q

What is immunoglobulin that is membrane bound

A

B-cell receptor

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6
Q

What is the function of immunoglobulin

A

Both BCR and secreted Ab bind Ag, Ag binding to the BCR signals B cell to: divide, differentiate, secrete Ab

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7
Q

What is the basic structure of antibody

A

Two identical heavy chains and two identical light chains

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8
Q

What are the divisions of Light chains of antibodies

A

Variable region (both on light and heavy), and constant region

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9
Q

What is a characteristic of variable region

A

varies between different B-cells (daughter B cells are identical)

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10
Q

What is a characteristic of a Constant region

A

Ab from same animal have similar constant region

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11
Q

What is a paratope

A

combined portion of light and heavy variable regions of antibody, 2 identical Ag binding sites per core Ab structure

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12
Q

What does the flexible portion on constant region of heavy chain do

A

allows better binding of antibody in diverse situations

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13
Q

What are the 5 major classes of antibody

A

IgM, IgG, IgD, IgE, IgA

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14
Q

Where are the differences in the isotypes of antibodies

A

in the constant region

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15
Q

Antibodies from the daughter cell have…..

A

different isotypes, but only one specificity

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16
Q

Characteristics of IgM

A

pentamer, 10 binding sites, high avidity, first Ab produced in immune response

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17
Q

Where is IgM found

A

serum and lymph

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18
Q

What is the first antibody produced

A

Igm

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19
Q

What does IgM do

A

Activate complement

20
Q

How many binding sites does IgM have

A

10

21
Q

How many binding sites does IgG have

A

2

22
Q

Where is IgG found

A

Serum, lymph, and tissue

23
Q

What is valence

A

how many binding sites on Ab are available

24
Q

What is the valence of IgG

A

2

25
Q

What is the valence of IgD

A

2

26
Q

Where is IgD found

A

Surface of B-cells

27
Q

What is the valence of IgE

A

2

28
Q

Where is IgE found

A

mucosa (bound to mast cells and basophils)

29
Q

What is the function of IgE

A

allergic reactions, response against helminthes

30
Q

What is the most common form of IgA

A

dimer

31
Q

What is the valence of IgA

A

4 (dimer form)

32
Q

Where is IgA found

A

Mucosal surfaces and secretions (tears/milk) and serum

33
Q

What does the paratope do

A

gives the Ab specificity for just one epitope

34
Q

What is cross reactivity

A

Specific Ab recognizes a second similar epitope

35
Q

What is the disadvantage of cross reactivity

A

Autoimmunity and diagnostic tests

36
Q

What is and advantage of cross reactivity

A

Immunizations

37
Q

What kind of affinity does cross reactivity have

A

low affinity (epitope not optimal, but good enough)

38
Q

What is affinity

A

Binding strength between epitope and paratope

39
Q

What is avidity

A

The sum total binding strength of all paratopes combined (ex. low affinity IgM may bind stronger than high affinity IgG because more valences[branches] so IgM>IgG avidity sometimes)

40
Q

What does signaling B cell via B-cell receptor do

A

Divide, differentiate, and secrete Ab

41
Q

What does opsonization do to antigen

A

enhances phagocytosis by macrophages and PMN by Fc receptors

42
Q

What can Ab do to toxins/viruses

A

Inhibit effects of toxins/viruses by binding to it

43
Q

What does Ab do to complement

A

begins the complement cascade

44
Q

What does Ab do to mast cells and with what does it work with

A

Degranulates mast cells, special Fc receptors on mast cells preloaded with IgE (allergies)

45
Q

What are immunoglobulin

A

Antigen recognition molecule of B cell

46
Q

Antibodies are always part of what immune response

A

Active

47
Q

Immune complex formation is what

A

Aggregation of Ag. Can be good or bad