Antigen Recognition and Receptor Diversification

Question 1

_____ cells differentiate into plasma cells to produce antibodies

Answer 1

B cells

Question 2

Specificity for individual pathogens is achieved through _____ on lymphocyte surfaces

Answer 2

• Antigen receptors
  
  • Antibody (BCR)
  • T cell receptor (TCR)

Question 3

Heavy and light chains of antibodies are held together by interchain ______ bonds

Answer 3

Dilsulfide

Question 4

What is the funciton of the hinge region of antibodies?

Answer 4

Allows antibody to bind with both arms to many different arrangements of antigens on the surfaces of pathogens

Question 5

What is the difference between the Fab and Fc regions of antibodies?

Answer 5

• Fab: fragment antigen binding; 2 identical fragments that bind antigen
• Fc: fragment crystallizable; 1 fragment responsible for destroying or clearing antigens from our bodies (effector functions)

Question 6

What protease digests antibodies into Fab and Fc fragments?

Answer 6

Papain

Question 7

How many complementary determining regions (CDRs) are there on an antibody?

Answer 7

3 on each heavy and light chain

Question 8

Class of antibody is determined by the constant region of the _____ chain.

Answer 8

Heavy

Question 9

What is the difference between kappa and lambda light chains?

Answer 9

Unknown functional difference

Question 10

What is the difference between an antigen and an epitope?

Answer 10

• Antigen: a substance that serves as a target for antibodies
• Epitope: the region on an antigen to which the antibody binds

Question 11

Antigenic determinants (epitopes) are usually _____ amino acids long

Answer 11

7-15

Question 12

What is the difference between affinity and avidity?

Answer 12

• Affinity: the ability of an antibody to bind an antigen
• Avidity: sum of individual affinity

Question 13

Diversity of antibodies is concentrated in what gene?

Answer 13

CDR3

Question 14

________ of gene segments creates enormous diversity in the antigen-binding sites of immunoglobulins

Answer 14

Random recombination

Question 15

B-cell receptors (BCRs) present on naive B-cells are composed of _____

Answer 15

Membrane-bound IgM and IgD

Question 16

______ trigger signal transduction on B-cells to start differentiating into plasma cells.

Answer 16

Igα and Igβ

Question 17

What is somatic hypermutation?

Answer 17

Targeted introduciton of point mutations into V regions of the H and L chains, leadinging to increased antibody affinity

Question 18

What enzyme carries out somatic hypermutation? What is its function?

Answer 18

Activation-induced Cytidine Deaminase (AID)

Deaminates C → U

Question 19

What is isotype switching?

Answer 19

Immunoglobulins changing class via changes in the constant region

Question 20

Which classes of antibodies are always made first and together? Which are made downstream?

Answer 20

• IgM and IgD made first
• IgE, IgG, and IgA made downstream

Question 21

• Monomer on B-cell (BCR)
• Pentamer in serum
• Neutralization of pathogen/toxic

Answer 21

IgM

Question 22

• Monomer in serum, dimer in secretions
• More of this Ig than any other in the body
• Major form of immunity at mucosal surfaces

Answer 22

IgA

Question 23

• 4 subclasses
• Longest ½ of any Ig (passive immunization)
• Neutralization and opsonization
• Can cross lacenta

Answer 23

IgG

Question 24

• Monomer
• Binds to basophil via Fc region
• Participates in immunity in the respiratory tract

Answer 24

IgD

Question 25

• Monomer
• Binds to mast cells via the Fc region
• Provides immunity against parasitic infections
• Least abundant in serum

Answer 25

IgE