Immunoglobulin Structure

Question 1

What is the general structure of antibodies?

Answer 1

Antibodies have 2 light and 2 heavy chains
and they are identical and held together by
disulfide bonds

Question 2

What part of the antibody is variable and reacts to antigens?

Answer 2

The N terminal end of the antibody

Question 3

How many antigens can one antibody bind?

Answer 3

Two as there are two sites

Question 4

How many types of antigens can an antibody bind?

Answer 4

One

Question 5

How many types of antibodies can a single antigen bind

Answer 5

Many

Question 6

What separates the classes of antibodies?

Answer 6

Antibody classes differ based on the constant

region of the antibody

Question 7

What is Fab?

Answer 7

Fab - antigen binding fragment

Question 8

What is Fc?

Answer 8

Fc - crystallized fragment (constant fragment)

Question 9

What are the classes of antibodies?

Answer 9

IgG
IgA
IgM
IgE
IgD

Question 10

What is the function of the hinge region?

Answer 10

Flexibility in binding antigens

Question 11

What structure is IgM often found as?

Answer 11

Pentameric with the J chain

Question 12

What structure is IgA often found as?

Answer 12

Dimeric with J chain

Question 13

Where is IgA found as a monomer?

Answer 13

In the blood

Question 14

Where is IgA found as a dimer?

Answer 14

Mucosal areas like eyes, nasal area and gut -> known as secretory IgA

Question 15

What is the function of the secretory component on dimeric IgA?

Answer 15

Protects IgA from proteolytic secretions in the stomach and gut

Question 16

What antibody class is not found in the serum?

Answer 16

IgD

Question 17

Where is IgD found?

Answer 17

IgD is antibodies on surface of B cells

Question 18

What is the major antibody class in the blood?

Answer 18

IgG

Question 19

What is the only antibody class to cross the placenta?

Answer 19

IgG

Question 20

What is IgE responsible for?

Answer 20

Allergies

Question 21

How does IgE cause allergies?

Answer 21

IgE binds to mast cells but nothing happens with IgE bound until an allergen binds and cross linking occurs between the IgEs then degranulation of the mast cells occurs

Question 22

What is the predominant Ab induced in primary response?

Answer 22

IgM

Question 23

What is the predominant Ab induced in secondary response?

Answer 23

IgG

Question 24

What are the 3 methods by which antibodies mediate humoral immunity?

Answer 24

Neutralization
Opsonization
Complement Activation

Question 25

What are the levels of antibodies like just prior to birth?

Answer 25

Maximum levels of maternal IgG and the levels drop rapidly after birth and 6-9 months is a critical period

Question 26

What are polyclonal antibodies?

Answer 26

Ab from multiple clones of B cells

Question 27

What is intravenous immunoglobulin?

Answer 27

It is polyclonal antibodies pooled from many sources (10000 individuals) used to treat many types of diseases

Question 28

What determines the isotope (class) of antibody?

Answer 28

The heavy chain

Question 29

What are the classes of light chains?

Answer 29

Lambda and kappa

Each member of a light-chain isotype shares complete amino acid sequence identity of the carboxy terminal C region with all other members of that isotype.

Question 30

What is the variable region of the antibody?

Answer 30

The combination of the variable region of the H chain and the variable region of the L chain make up the antigen binding site of an immunoglobulin.