Unit 7 Antibodies I Structure and Function Flashcards Preview

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Flashcards in Unit 7 Antibodies I Structure and Function Deck (45):
1

term antibodies is used in context of

antigens eg an antibody to antigen such as bacterium

2

term Ig is used when

to emphasize antibodies are globulin proteins produced by immune system

3

Ig are made up of

one pair of identical heavy chains and light chains

4

each chain is divided into

constant (C) and variable (V) regioons

5

what is variable region

high degree of variations among Ig. where the ABS is located (specificity)

6

what is constant region

same/constant among class of Ig (eg all IgM have same heavy chain constant region)

7

constant region is associated with

biological fn that could be unique to particular Ig class

8

light chains are further divided into

2 domains VL and CL

9

heavy chains are further divided into

4 domains Vh Ch1 Ch2 Ch3

10

eg the antigen binding site can be represented as

VL + Vh

11

enzyme papain cleaves Ig molecule into 3 fragments:

2 Fab and 1 Fc

12

composition of the 2 Fab fragments

VL Cl Vh and CH1 domains

13

composition of 1 Fc fragment

Ch2 and Ch3

14

enzyme pepsin cleaves Ig into

1 F(ab')2 fragment (contains intact ABS) and 1 pFc' fragment

15

constant region could contain (3)

1. receptors for complement
2. site that interacts w/transport protein in placenta to antibodies (IgG only)
3. receptors for macrophages, granulocytes or mast cells

16

IgG (and C3b) can act as _ to do what

opsonin. help macrophage capture pathogen more easily

17

Ig are classified into 5 classes according to

constant region of heavy chains

18

Ig classes

IgG (four subclasses) IgA (2)
IgM, IgD, IgE

19

what is hypervariable region

variable regions of light (VL) and heavy chains (Vh) which contain ABS

20

features of IgG

most common in blood, major Ab of 2nd immune response, opsonin, when complexed w/Ag activates classical complement pathway, agglutinate antigen, pass through placenta passive immunity

21

IgG through placenta is what type of immunity

naturally acquired passive immunity

22

features of IgA

in seromucous secretions, saliva colostrum etc

23

structure of secretion IgA

2 IgA joined (dimer) together by joining chain

24

list benefits of secretory IgA

naturally acquired passive. lower incidence of GI and respiratory infections among breastfed

25

features of IgM

pentamer. activate classical complement, first Ig that appears in primary immune response. effective agglutinating Ab

26

IgM as a monomer found on

membrane of mature B lymphocytes. acts as cell surface receptors for antigens

27

why is IgM so effective an agglutinating

multple ABS allows attachment of many antigen

28

features of IgD

cell surface receptors for antigens on B cells

29

features of IgE

scarce in peripheral blood, w/eosinophils defend against parasitic worms, w/basophil or mast cell responsible for allergy

30

how is in vitro test of Type 1 allergy performed

checking serum level of total IgE or allergen specific IgE

31

effect of eosinophil binding to Fc of IgE

frustrated phagocytosis against big worm ->release granules of destructive enzymes

32

major fn of antibody (humoral) immune response (5)

neutralization, opsonization, activation of classical complement, agglutination, antibody dependent cell mediated cytotoxicity ADCC

33

what is neutralization (anti-adhesion)

block attachment of microorganism to susceptible cells (viral). block binding of microbial products such as toxins to target cells

34

what is opsonization

phagocytes are more effective in capturing extracellular Ag when coat with IgG

35

activation of classical complement by forming of Ab-Ag complex leads to

chemotaxis, inflammation, opsonization, and formation of MAC

36

agglutination is helpful how

increased number of antigens can be phagocytized when agglutinated

37

what is antibody dep. cell med. cytotoxicity ADCC

PMNs, macrophages, NK cells have receptors for constant region of Ab. when bind to Ab attached to org can kill them more effectively

38

primary vs secondary humoral response

primary generated following first encounter of antigen. secondary generated after in subsequent exposures

39

what is lag or latent phase

stage where no antibody is detected in blood/plasma

40

what is seroconverson

from sero -ive (no Ab detected) to sero +ive (Ab detected)

41

testing during lag/latent phase gives what results

false -ive. infected but pathogen-specific Ab not detectable

42

what is log phase

antibody titre (level) increases exp

43

what is paired sera

serum taken during acute (illness/lag) and convalescent (recovered/log) phase to see evidence of infection

44

what is plateau phase

when antibody titre reaches max and stabalizes

45

what is decline phase

Ab is catabolized and returns to lower level