Lecture 15

Question 1

List the non-covalent bonds in the order of relative importance.

Answer 1

1. Hydrophobic bonds
2. Hydrogen bonds
3. Electrostatic bonds
4. Van der Waals bonds

Question 2

What type of bond links the antigen with its receptor?

Answer 2

Non-covalent bonds

Question 3

What is comninatorial association?

Answer 3

The processes in which antigen receptor chains may be paired in different combinations to yield even greater diversity.

Question 4

How many genes code for the variable chain? for the constant chain?

Answer 4

Several; one

Question 5

What are the 7 methods of generating immunoglobulin diversity?

Answer 5

1. VJ and VDJ gene recombination
2. Base deletion
3. Base insertion
4. Somatic mutation
5. Combinatorial association
6. Gene conversion
7. Receptor editing

Question 6

What is the process of gene recombination?

Answer 6

1. Random selection of one gene from each of several groups of genes.
2. Recombining these selected genes.
3. Sequence diversity

Question 7

Which gene is NOT present in light chains?

Answer 7

D gene

Question 8

How is the class of Immunoglobulin determined?

Answer 8

By the constant region in the heavy chain.

Question 9

What are the three gene loci codes for the immunoglobulin peptide chains? and what do they code for?

Answer 9

IGK - kappa light chains
IGL - lambda light chains
IGH - heavy chains

Question 10

What two enzymes are used in looping out?

Answer 10

Recombinase (RAG1, RAG2) and DNA repair enzymes (ligases)

Question 11

What are the steps of constructing an immunoglobulin light chain?

Answer 11

1. DNA rearrangement
2. Transcription
3. RNA splicing
4. Translation

Question 12

What are the steps of constructing an immunoglobulin heavy chain?

Answer 12

1. DNA rearrangement I
2. DNA rearrangement II
3. Transcription
4. RNA splicing
5. Translation

Question 13

How many attempts does a B cell have to make a productive gene?

Answer 13

Four

Question 14

What is the process for a heavy chain isotype switch?

Answer 14

1. Signals from helper T-cells (CD40 ligand, cytokines)
2. Induction of AID
3. Recombination of Su with Sy, deletion of intervening C genes.
4. Transcription; RNA splicing
5. Translation

Question 15

What is the major difference in the variable regions of TCR and immunoglobulins?

Answer 15

Immunoglobulins have multiple CDR’s that are formed by somatic mutation or gene conversion.
TCR’s have one CDR that is formed by recombination of V, (D), and J gene segments

Question 16

What are the three lymphoid organs that generate diversity and how do they accomplish this?

Answer 16

• Bone marrow - gene recombination
• Bursal equivalent - Gene conversion and cell selection
• Lymph node/germinal center - gene conversion or somatic mutation

Question 17

What are the methods of generating TCR diveristy?

Answer 17

1. VJ, VJJ, VDJ, and VDDJ gene recombination
2. Base deletion
3. Base insertion
4. Combinatorial association

Question 18

Define antigen specificity.

Answer 18

The antigen binding site is specific to that antigen.

Question 19

Define generation of diversity.

Answer 19

Through each stage of antigen construction the genes needed are randomly selected, as well as other processes that play a role in the genetic combination, which contribute to the diversity of the antigen.

Question 20

Define somatic mutation.

Answer 20

Any alteration in the genes in the tissues after fertilization.

Question 21

What is gene conversion?

Answer 21

The process in which pseudogenes are taken and used to replace other genes within certain areas of the DNA sequence.