B Cells 3

Question 1

what is the shape of an antibody?

Answer 1

Y

Question 2

what type of molecule are antibodies?

Answer 2

glycoproteins

Question 3

what is immunoglobulin?

Answer 3

protein family that antibodies and BCRs are part of

Question 4

describe the structure of antibody in terms of chains

Answer 4

• 2 identical disulfide-linked heavy chains
• 2 identical light chains

Question 5

describe the structure of antibody in terms of regions

Answer 5

VARIABLE regions –> heavy and light chains both have a variable region for antibody binding (V_L, V_H)

CONSTANT regions –> heavy and light chains both have a constant region (C_L, C_H)

Question 6

what is the function of the variable region?

Answer 6

Ag binding

Question 7

how many variable regions are there in an antibody?

Answer 7

2 identical variable regions –> therefore 2 identical binding sites

Question 8

what does Ag binding lead to?

Answer 8

neutralization

Question 9

what is the function of the constant region?

Answer 9

involved in complement activation

Question 10

what is the constant region called?

Answer 10

Fc

Question 11

what does the constant region do? and 2 functions

Answer 11

Fc binds Fc receptors on phagocytes and other cell types to lead to intracellular signaling

1. C1q binds to activate complement
2. help mast cells get rid of helminth
3. opsonization for phagocyte

Question 12

what are the 2 fragments of antibody?

Answer 12

1. Fab fragments
2. Fc fragments

Question 13

how many Fab fragments per antibody?

Answer 13

2

Question 14

what does Fab stand for?

Answer 14

Fragment antigen binding

Question 15

what parts of the antibody are in Fab fragments?

Answer 15

has the antigen-binding domain (variable region) and part of the constant H and L chains

Question 16

how many Fc fragments are there?

Answer 16

1

Question 17

what does Fc stand for?

Answer 17

Fragment crystallizable

Question 18

what parts of the antibody are in the Fc fragment?

Answer 18

constant regions of the heavy chain

Question 19

which fragment is recognized by receptors that bind antibodies?

Answer 19

Fc fragment

Question 20

what type of bond holds antibody together?

Answer 20

disulfide covalent bonds

Question 21

what type of 3D structures are antibodies folded into?

Answer 21

Beta sheets

Question 22

what does CDR stand for?

Answer 22

Complementarity Determining Region

Question 23

what is CDR?

Answer 23

Antibody-antigen binding site –> direct contact with Ag

Question 24

what is the structure of CDR?

Answer 24

3 hypervariable loops per variable domain and are not part of the B strands

Question 25

which part of antibodies have the greatest variability in the antibody sequence? why?

Answer 25

complementarity determining region to allow binding to diff antigens

Question 26

where is CDR located on the antibody?

Answer 26

at the extremities of the antibody --> i.e. extremities are responsible for antibody:antigen binding

Question 27

what type of binding occurs between the Ig and epitope? and 4 examples

Answer 27

NON-COVALENT BINDING 1. H bonds 2. van der Waals 3. Hydrophobic 4. Ionic

Question 28

what is a way to describe specificity of the antibody:antigen binding?

Answer 28

lock and key

Question 29

what are 2 types of variability that affect antibody:antigen binding?

Answer 29

1. variability in size of epitope 2. variability in antibody --> CDR varies in length

Question 30

where are epitopes located on an antigen?

Answer 30

epitopes can be anywhere on an antigen --> antigen has many epitopes

Question 31

what are the 5 classes of antibody?

Answer 31

1. IgM 2. IgD 3. IgG 4. IgE 5. IgA

Question 32

what is the main difference btwn classes of antibody?

Answer 32

different # of Ig-like domains in the constant region of the heavy chain based on diff AA sequence

Question 33

is IgM a monomer?

Answer 33

no, it is a pentamer

Question 34

describe the structure of IgM pentamer

Answer 34

5 IgM antibodies linked together via disulfide bonds

Question 35

describe the heavy chain of IgM

Answer 35

1 variable region, 4 constant regions

Question 36

describe how IgM is expressed on mature B cells vs plasma cells

Answer 36

mature B cells express transmembrane IgM (monomer) prior to activation then B cell becomes plasma cell and forms pentamer

Question 37

IgM is part of which wave of secreted antibodies?

Answer 37

IgM is part of the first wave

Question 38

describe the heavy chain of IgD

Answer 38

1 variable region, 3 constant regions

Question 39

IgD is part of which wave of secreted antibodies?

Answer 39

IgD is part of the first wave

Question 40

describe the heavy chain of IgG

Answer 40

1 variable region, 3 constant regions

Question 41

IgG is the most abundant in ______

Answer 41

IgG is the most abundant in plasma fluid

Question 42

how many IgG subclasses are there? what is the difference btwn them

Answer 42

4 --> each with slightly diff functions

Question 43

when is IgG produced?

Answer 43

after differentiation in the germinal center --> not 1st wave

Question 44

describe the heavy chain of IgE

Answer 44

1 variable region, 4 constant regions

Question 45

when is IgE produced?

Answer 45

to help Th2 get rid of Helminth infections

Question 46

describe the heavy chain of IgA

Answer 46

1 variable region, 3 constant regions

Question 47

describe the structure of IgA in plasma

Answer 47

monomer

Question 48

describe the structure of IgA in mucous secretions in GIT and respiratory system

Answer 48

dimer

Question 49

how does IgA become a dimer?

Answer 49

linking via J chain

Question 50

IgA is important for which type of immunity?

Answer 50

mucosal immunity

Question 51

how many subclasses of IgA are there?

Answer 51

2

Question 52

why can antibodies be used as a drug? and an example?

Answer 52

antibodies can bind to any epitope --> ex. antibody against TNFalpha for rheumatoid arthritis

Question 53

how are antibodies used in research?

Answer 53

ELISA assay or WB where an antibody conjugated with fluorescence can bind the Fc region of another antibody

Question 54

why can an antibody therapy cause an immune response?

Answer 54

if the antibody is less similar to humans, your immune system can mount an immune response against it