L4_Antibody Structure and Function

Question 1

Which chains contain variable regions and how many hypervariable regions do they have?

Answer 1

Both the light and heavy chain have variable regions with 3 hypervariable regions

Question 2

Which chain can be variably labeled with Carbohydrates?

Answer 2

The heavy chain.

Question 3

What chain defines the class of an antibody?

Answer 3

Heavy

Question 4

Are the light and heavy chains made by the same or separate genes?

Answer 4

Separate.

Question 5

What are the two types of light chains?

Answer 5

lambda and kappa

Question 6

What are the different types of heavy chains how many subunits for each type?

Answer 6

M(5) , D(4), G(4), A(4), E(5)

Question 7

On average what is the molecular weight of an antibody, what is the exception

Answer 7

~150kDa (IgM 1000kDa due to pentamer formation)

Question 8

What subclass of Antibody is most abundant in the serum, least abundant?

Answer 8

IgG is most IgE is least

Question 9

Which type of antibody is responsible for activating mast cells triggering an allergic reaction?

Answer 9

IgE

Question 10

What types of antibody are mainly responsible for neutralization?

Answer 10

IgG and IgA (weak IgM)

Question 11

What two types of IgG are mainly responsible for opsonization?

Answer 11

IgG1 and IgG3 (weak IgG4 and IgA)

Question 12

What types of antibodies mainly activate the complement system?

Answer 12

IgM, IgG1, IgG3 (weak IgA and IgG2)

Question 13

What type of antibody diffuses across the placenta?

Answer 13

IgG (IgG1 the strongest IgG2 the weakest)

Question 14

What type of antibody can cross epithelium the easiest and is found in mothers breast milk? Which form of it?

Answer 14

IgA dimers

Question 15

What type of antibodies diffuse into extravascular space?

Answer 15

All IgG and IgA monomers. (weak IgE)

Question 16

What is the region called where the heavy chains are linked by disulfide bonds on IgG?

Answer 16

Hinge Region

Question 17

Name the functions/capabilities of IgG

Answer 17

Toxin neutralizing, agglutinating, opsonizing, bacteriolytic (with aid of complement system)

Question 18

Do immune cells have IgM receptors?

Answer 18

No

Question 19

Name the functions/capabilities of IgM

Answer 19

Antigen receptor on B-cells and agglutinating. Only with the aid of complement can it be opsonizing or bacteriolytic (Immune cells do not have IgM receptors)

Question 20

Does IgM have a hinge region?

Answer 20

NO

Question 21

What chain is involved when IgM and IgA form multimers?

Answer 21

J Chain

Question 22

What type of Ab is predominant in secretions?

Answer 22

IgA (dimers)

Question 23

What are the main functions of IgA

Answer 23

agglutinating, neutralization, and opsonization

Question 24

What piece of IgA aids in secretion and what does it do?

Answer 24

T-Piece resists acid hydrolysis

Question 25

What does Papain do? What does Pepsin do?

Answer 25

Papain digests hinge region(3 fractions 1 Fc and 2 Fab). Pepsin digests heavy chain starting at C-terminus and ending at interchain disulfides (1fraction Fab2)

Question 26

What are the residues in the variable region that do not vary much referred to as?

Answer 26

Framework residues

Question 27

What does IgE do?

Answer 27

Immediate hypersensitivity, fixes to mast cells, mediates changes in vascular permeability.

Question 28

What antibody is the most potent at complement fixation?

Answer 28

IgM