W3-3 B Lymphocyte Biology
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Questions and Answers

What is the role of RAG-1 and RAG-2 proteins in gene segment rearrangement?

  • They inhibit the function of terminal deoxynucleotidyl transferase (TdT)
  • They increase the rate of somatic hypermutation
  • They act as repressors of gene segments
  • They separate, shuffle, and rejoin the VDJ genes (correct)

    • Which enzyme is responsible for adding random nucleotides at the junctions of gene segments?

  • Exonuclease
  • RAG-1
  • Terminal deoxynucleotidyl transferase (TdT) (correct)
  • RAG-2

    • What function does somatic hypermutation serve in antibody diversity generation?

  • It generates additional copies of VDJ gene segments
  • It introduces point mutations in the variable region of antibody genes (correct)
  • It increases the frequency of VDJ gene segment rearrangement
  • It prevents exonuclease from removing nucleotides

    • What would be the consequence of not possessing a functional CD40 or CD40L?

    <p>Inability to engage in T-B cell interaction</p> Signup and view all the answers

    What is the role of RAG-1 and RAG-2 proteins in gene segment rearrangement?

    <p>They control the random recombination of VJ and VDJ gene segments</p> Signup and view all the answers

    How is somatic hypermutation accomplished?

    <p>By introducing point mutations in the rearranged VDJ genes</p> Signup and view all the answers

    Which event is controlled by the enzymes RAG-1 and RAG-2?

    <p>Random recombination of VJ and VDJ gene segments</p> Signup and view all the answers

    What is the role of terminal deoxynucleotidyl transferase (TdT) in B cell development?

    <p>It adds non-template nucleotides to the junctions of V, D, and J gene segments</p> Signup and view all the answers

    What is the role of RAG-1 and RAG-2 proteins in gene segment rearrangement?

    <p>They function to separate, shuffle, and rejoin the VDJ genes</p> Signup and view all the answers

    What is the difference between ‘junctional diversity’ and ‘combinatorial diversity’?

    <p>Junctional diversity occurs from the joining of gene segments with random nucleotide insertions, while combinatorial diversity arises from the random recombination of gene segments</p> Signup and view all the answers

    How is germline diversity generated in the heavy chain genes compared to the light chain genes?

    <p>Heavy chain genes are made of V, D, and J segments while light chain genes are made of only V and J segments</p> Signup and view all the answers

    What happens as a result of the random recombination of the various VJ and VDJ gene segments?

    <p>It leads to combinatorial diversity</p> Signup and view all the answers

    What is the first antibody produced by the B cell progeny after encountering its specific antigen?

    <p>IgM</p> Signup and view all the answers

    Which enzyme mediates the process of somatic hypermutation in B cells?

    <p>Activation-induced cytidine deaminase (AID)</p> Signup and view all the answers

    What type of antigen response does not require somatic hypermutation in the responding B cell?

    <p>T-independent antigen</p> Signup and view all the answers

    What controls the synthesis of the enzyme activation-induced cytidine deaminase (AID) during somatic hypermutation?

    <p>IL-4 and CD40 activation signals</p> Signup and view all the answers

    What is the significance of B cell receptor (BCR) cross-linking with antigen?

    <p>It activates somatic hypermutation in the B cell</p> Signup and view all the answers

    What is the role of activation-induced cytidine deaminase (AID) in B cell development after antigen contact?

    <p>It induces somatic hypermutation and class switch recombination in the B cell</p> Signup and view all the answers

    What occurs as a result of class switch recombination in B cell development after antigen contact?

    <p>Production of different antibody isotypes with distinct effector functions</p> Signup and view all the answers

    Which process is responsible for enhancing the binding affinity of antibodies to a specific antigen after B cell development following antigen contact?

    <p>Somatic hypermutation</p> Signup and view all the answers

    What are the 3 signals required for activation of a B cell following interaction with a T-dependent antigen?

    <p>Presentation of peptide with MHC to the B cell receptor, activation of CD40 upon binding with CD40L, and cytokine binding to its receptor on the B cell</p> Signup and view all the answers

    Which type of antigens lead to B cell response in the absence of T cell help, resulting in only low affinity IgM antibody production?

    <p>T-independent antigens</p> Signup and view all the answers

    What events occur only with cooperation between B cells and T cells following interaction with a T-dependent antigen?

    <p>Affinity maturation, isotype switching, and delivery of 3 signals from activated CD40 upon binding with CD40L of the T cell</p> Signup and view all the answers

    Study Notes

    • Dr. Raymond F. Adebiyi's lecture focuses on the core concepts of the generation of diversity in immunoglobulins.
    • Two types of diversity: germline and combinatorial.
    • Germline diversity arises from the presence of multiple copies of V, D, and J gene segments in heavy and light chain genes.
    • Heavy chains have V, D, and J segments, while light chains have only V and J segments.
    • Combinatorial diversity occurs through the random recombination of various VJ and VDJ gene segments, controlled by RAG-1 and RAG-2 proteins, which function to separate, shuffle, and rejoin VDJ genes.
    • Junctional diversity refers to the unique sequence produced when V, D, and J segments are joined, while combinatorial diversity comes from the combination of different V, D, and J segments.
    • Terminal deoxynucleotidyl transferase (TdT) and exonuclease play roles in creating diversity by adding nucleotides and removing nucleotides, respectively, at the junctions of gene segments during rearrangement.
    • Somatic hypermutation and isotype switching are processes that further diversify the immune response. Somatic hypermutation increases the variability of antibodies, while isotype switching allows for the production of different classes of antibodies in response to antigenic stimulation.
    • A deficiency in RAG-1, RAG-2, AID, CD40, or CD40L can result in various immune disorders.
    • B cell development occurs in two stages: before and after contact with antigen. The events before antigen contact involve the random recombination of gene segments to generate diverse antibodies, while those after antigen contact involve the maturation and activation of B cells.

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    Related Documents

    B Lymphocyte Biology PDF

    Description

    Test your understanding of the generation of diversity in immunoglobulin heavy and light chains, including the role of RAG-1 and RAG-2 proteins, junctional diversity, combinatorial diversity, terminal deoxynucleotidyl transferase (TdT), exonuclease, somatic hypermutation, and isotype switching.

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