Antigens & Antigen Receptors Lecture B
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Questions and Answers

What term describes the expression of multiple genes with the same function?

  • Polygenic (correct)
  • Monogenic
  • Heterozygous
  • Dominant

    • Why is tissue typing essential in organ transplantation for MHCs?

  • To avoid rejection of the organ as 'non-self' (correct)
  • To test for blood type compatibility
  • To match the color of the organ to the recipient
  • To increase the chances of organ acceptance

    • Which type of cells contain MHC class I, making tissue typing vital in organ transplants?

  • Platelets
  • Red blood cells
  • Skin cells
  • All nucleated cells (correct)

    • What process leads to a higher number of possible BCRs/Igs due to changes in their sequences?

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

    Which segments are present in the immunoglobulin genes that participate in gene rearrangement?

    <p>VDJ segments</p> Signup and view all the answers

    What is the term for the protein chains in both BCR and TCR that have variable regions based on the Ig fold?

    <p>Immunoglobulin chains</p> Signup and view all the answers

    What is the primary function of the MHC Class I antigen presentation pathway?

    <p>To present endogenous antigens derived from virally infected cells, tumor cells, or intracellular pathogens to cytotoxic T cells for elimination</p> Signup and view all the answers

    Which component facilitates the replacement of CLIP with antigenic peptides during MHC Class II antigen presentation?

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

    What is the typical length of peptides presented by MHC Class I molecules?

    <p>8-10 amino acids</p> Signup and view all the answers

    Which pathway is responsible for presenting antigens derived from extracellular pathogens to helper T cells for antibody production?

    <p>MHC Class II pathway</p> Signup and view all the answers

    What is the typical length of peptides presented by MHC Class II molecules?

    <p>13-18 amino acids</p> Signup and view all the answers

    Which component of the MHC Class I antigen presentation pathway is responsible for stabilizing the peptide-MHC complex before transport to the cell surface?

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

    What is the primary mechanism by which diversity in T cell receptors (TCRs) and B cell receptors (BCRs) is achieved?

    <p>Random combination of different gene segments for each receptor</p> Signup and view all the answers

    Which of the following statements about B cell development in the bone marrow is correct?

    <p>The heavy chain genes are rearranged before the light chain genes</p> Signup and view all the answers

    In the context of T cell development in the thymus, what does the abbreviation 'DN' stand for?

    <p>Double negative, referring to cells not expressing CD4 or CD8</p> Signup and view all the answers

    Which of the following statements about the heavy chain of the T cell receptor (TCR) is correct?

    <p>The heavy chain utilizes a similar mechanism to the B cell receptor (BCR) for gene rearrangement</p> Signup and view all the answers

    Which of the following processes is responsible for removing self-reactive B cells during development?

    <p>Negative selection</p> Signup and view all the answers

    Which statement about the HLA complex is correct?

    <p>It contains genes encoding both MHC Class I and MHC Class II molecules.</p> Signup and view all the answers

    Which of the following statements about MHC genes is incorrect?

    <p>Most humans are homozygous for MHC haplotypes.</p> Signup and view all the answers

    Which of the following statements about MHC molecules is correct?

    <p>MHC Class II molecules are formed of two polypeptide chains, one with $\alpha1$ and $\alpha2$ domains, and the other with $\beta1$ and $\beta2$ domains.</p> Signup and view all the answers

    Which of the following statements about antigen presentation is incorrect?

    <p>Professional antigen-presenting cells (APCs) play no role in antigen presentation.</p> Signup and view all the answers

    Which of the following genes are not part of the HLA complex?

    <p>HLA-X, HLA-Y, HLA-Z</p> Signup and view all the answers

    According to the information provided, how many MHC alleles have been identified so far?

    <p>15,000 alleles</p> Signup and view all the answers

    Which of the following statements accurately describes the structure of MHC class I molecules?

    <p>They are composed of two polypeptide chains, an α chain and a β2-microglobulin, both encoded by multiple genes.</p> Signup and view all the answers

    Which of the following cells are responsible for presenting exogenous antigens to CD4+ T helper cells via MHC class II molecules?

    <p>Macrophages and dendritic cells</p> Signup and view all the answers

    What is the primary function of dendritic cells in the context of antigen presentation?

    <p>To capture and present both endogenous and exogenous antigens to CD4+ and CD8+ T cells via MHC class I and II molecules.</p> Signup and view all the answers

    Which of the following statements accurately describes the process of MHC class I antigen presentation?

    <p>Endogenous antigens are degraded in the cytosol, and the resulting peptides are transported to the endoplasmic reticulum (ER) for loading onto MHC class I molecules.</p> Signup and view all the answers

    What is the primary function of the T cell receptor (TCR) complex?

    <p>To recognize and bind to linear peptide epitopes presented by MHC molecules.</p> Signup and view all the answers

    Which of the following statements accurately describes the structure of MHC class II molecules?

    <p>They are composed of two polypeptide chains, an α chain and a β chain, both encoded by separate polymorphic genes.</p> Signup and view all the answers

    Calreticulin and Tapasin bind to create a 'peptide editing complex' in the process of MHC class II presentation.

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

    MHC class I presentation is focused on external pathogens such as viruses and bacteria.

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

    Peptides presented by MHC class II molecules are typically 13-18 amino acids in length.

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

    The primary function of MHC class I molecules is to trigger the production of antibodies by B cells.

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

    MHC class II molecules are mainly formed of one chain with a1, a2, and a3 domains.

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

    The replacement of CLIP with antigenic peptides during MHC Class II antigen presentation is facilitated by the protein DM.

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

    The diversity of MHC molecules within a population is due to them being monogenic.

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

    MHCs are expressed codominantly, which means all genes are expressed sequentially.

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

    Children express very similar MHC molecules to their parents due to the lack of diversity in MHCs.

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

    Both B cells and T cells express multiple receptors, each specific for multiple antigens.

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

    The number of possible TCRs is greater than the number of possible BCRs due to differences in their sequences.

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

    Somatic hypermutation and affinity maturation lead to a decrease in the diversity of BCRs/Igs.

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

    The T cell receptor binds linear arrays of approximately 9 amino acids via the TCR.

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

    Antigen presenting cells for T cells include macrophages and neutrophils.

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

    Epitopes are antigen binding sites on T cell receptors.

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

    MHC class I molecules present exogenous antigens to CD4+ T helper cells.

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

    Dendritic cells play a crucial role in antigen capture and presentation but are not found in lymph nodes.

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

    Antigen receptors on B cells and T cells function in exactly the same way.

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

    MHC Class I and MHC Class II molecules present protein antigens that are generated outside the cell.

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

    The MHC complex is located on Chromosome 6 in humans and contains genes only for the Major Histocompatibility Complex (MHC).

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

    MHC Class I and MHC Class II genes are monomorphic, resulting in limited diversity among individuals.

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

    Most humans are homozygous for their MHC alleles, inheriting the same polymorphisms from both parents.

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

    The HLA complex on Chromosome 6 contains only classical MHC genes, such as HLA-A, HLA-B, and HLA-C.

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

    Dendritic cells are not considered Professional Antigen-Presenting Cells (APCs) in the context of immune responses.

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

    Dendritic cells detach and enter the arterial vessels after processing the antigen at the site of infection.

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

    In the endogenous pathway, peptide antigens are produced by processing proteins through ubiquitination.

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

    Proteins are marked for degradation by a post-translational modification called phosphorylation in the exogenous pathway.

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

    Antigen:MHC I complexes are transported to the cell membrane in the endogenous pathway.

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

    The exogenous pathway involves loading peptides into MHC class II in the endoplasmic reticulum.

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

    MHC class I α chain associates with the chaperone protein Calreticulin in the antigen presentation process.

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

    Study Notes

    • Major Histocompatibility Complex (MHC) genes are polymorphic, polygenic, and expressed codominantly, leading to a huge diversity of MHC molecules within populations.
    • Children express different MHC molecules from their parents due to the polymorphic nature of MHC genes.
    • MHC class I is crucial for presenting antigens from endogenous sources (e.g., virally infected cells), activating cytotoxic T cells for cell killing.
    • MHC class II is essential for presenting antigens from exogenous sources (e.g., external pathogens) for immune responses mediated by antibodies and T helper cells.
    • B cells and T cells develop unique antigen receptors (BCRs and TCRs) through gene rearrangement, resulting in a vast number of possible receptors.
    • Antigen presentation by MHC class I and II is necessary for activating αβ T cells, leading to the appropriate immune response against presented antigens.
    • The Human leukocyte antigens (HLA) complex on Chromosome 6 in humans contains genes for MHC as well as other immune-related genes, showing high polymorphism and diverse haplotypes.

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    Antigens & Antigen Receptors Lecture B PDF

    Description

    Test your knowledge on Antigens & Antigen Receptors Lecture B delivered by Dr. Kikki Bodman-Smith and Dr. Natalie Riddell. This quiz covers topics such as MHC class I & II, Antigen processing and presentation, and Genetics of antigen recognition.

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