59 Questions
What term describes the expression of multiple genes with the same function?
Polygenic
Why is tissue typing essential in organ transplantation for MHCs?
To avoid rejection of the organ as 'non-self'
Which type of cells contain MHC class I, making tissue typing vital in organ transplants?
All nucleated cells
What process leads to a higher number of possible BCRs/Igs due to changes in their sequences?
Somatic hypermutation/affinity maturation
Which segments are present in the immunoglobulin genes that participate in gene rearrangement?
VDJ segments
What is the term for the protein chains in both BCR and TCR that have variable regions based on the Ig fold?
Immunoglobulin chains
What is the primary function of the MHC Class I antigen presentation pathway?
To present endogenous antigens derived from virally infected cells, tumor cells, or intracellular pathogens to cytotoxic T cells for elimination
Which component facilitates the replacement of CLIP with antigenic peptides during MHC Class II antigen presentation?
DM
What is the typical length of peptides presented by MHC Class I molecules?
8-10 amino acids
Which pathway is responsible for presenting antigens derived from extracellular pathogens to helper T cells for antibody production?
MHC Class II pathway
What is the typical length of peptides presented by MHC Class II molecules?
13-18 amino acids
Which component of the MHC Class I antigen presentation pathway is responsible for stabilizing the peptide-MHC complex before transport to the cell surface?
Tapasin
What is the primary mechanism by which diversity in T cell receptors (TCRs) and B cell receptors (BCRs) is achieved?
Random combination of different gene segments for each receptor
Which of the following statements about B cell development in the bone marrow is correct?
The heavy chain genes are rearranged before the light chain genes
In the context of T cell development in the thymus, what does the abbreviation 'DN' stand for?
Double negative, referring to cells not expressing CD4 or CD8
Which of the following statements about the heavy chain of the T cell receptor (TCR) is correct?
The heavy chain utilizes a similar mechanism to the B cell receptor (BCR) for gene rearrangement
Which of the following processes is responsible for removing self-reactive B cells during development?
Negative selection
Which statement about the HLA complex is correct?
It contains genes encoding both MHC Class I and MHC Class II molecules.
Which of the following statements about MHC genes is incorrect?
Most humans are homozygous for MHC haplotypes.
Which of the following statements about MHC molecules is correct?
MHC Class II molecules are formed of two polypeptide chains, one with $\alpha1$ and $\alpha2$ domains, and the other with $\beta1$ and $\beta2$ domains.
Which of the following statements about antigen presentation is incorrect?
Professional antigen-presenting cells (APCs) play no role in antigen presentation.
Which of the following genes are not part of the HLA complex?
HLA-X, HLA-Y, HLA-Z
According to the information provided, how many MHC alleles have been identified so far?
15,000 alleles
Which of the following statements accurately describes the structure of MHC class I molecules?
They are composed of two polypeptide chains, an α chain and a β2-microglobulin, both encoded by multiple genes.
Which of the following cells are responsible for presenting exogenous antigens to CD4+ T helper cells via MHC class II molecules?
Macrophages and dendritic cells
What is the primary function of dendritic cells in the context of antigen presentation?
To capture and present both endogenous and exogenous antigens to CD4+ and CD8+ T cells via MHC class I and II molecules.
Which of the following statements accurately describes the process of MHC class I antigen presentation?
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.
What is the primary function of the T cell receptor (TCR) complex?
To recognize and bind to linear peptide epitopes presented by MHC molecules.
Which of the following statements accurately describes the structure of MHC class II molecules?
They are composed of two polypeptide chains, an α chain and a β chain, both encoded by separate polymorphic genes.
Calreticulin and Tapasin bind to create a 'peptide editing complex' in the process of MHC class II presentation.
False
MHC class I presentation is focused on external pathogens such as viruses and bacteria.
False
Peptides presented by MHC class II molecules are typically 13-18 amino acids in length.
True
The primary function of MHC class I molecules is to trigger the production of antibodies by B cells.
False
MHC class II molecules are mainly formed of one chain with a1, a2, and a3 domains.
False
The replacement of CLIP with antigenic peptides during MHC Class II antigen presentation is facilitated by the protein DM.
True
The diversity of MHC molecules within a population is due to them being monogenic.
False
MHCs are expressed codominantly, which means all genes are expressed sequentially.
False
Children express very similar MHC molecules to their parents due to the lack of diversity in MHCs.
False
Both B cells and T cells express multiple receptors, each specific for multiple antigens.
False
The number of possible TCRs is greater than the number of possible BCRs due to differences in their sequences.
True
Somatic hypermutation and affinity maturation lead to a decrease in the diversity of BCRs/Igs.
False
The T cell receptor binds linear arrays of approximately 9 amino acids via the TCR.
True
Antigen presenting cells for T cells include macrophages and neutrophils.
False
Epitopes are antigen binding sites on T cell receptors.
False
MHC class I molecules present exogenous antigens to CD4+ T helper cells.
False
Dendritic cells play a crucial role in antigen capture and presentation but are not found in lymph nodes.
False
Antigen receptors on B cells and T cells function in exactly the same way.
False
MHC Class I and MHC Class II molecules present protein antigens that are generated outside the cell.
False
The MHC complex is located on Chromosome 6 in humans and contains genes only for the Major Histocompatibility Complex (MHC).
False
MHC Class I and MHC Class II genes are monomorphic, resulting in limited diversity among individuals.
False
Most humans are homozygous for their MHC alleles, inheriting the same polymorphisms from both parents.
False
The HLA complex on Chromosome 6 contains only classical MHC genes, such as HLA-A, HLA-B, and HLA-C.
False
Dendritic cells are not considered Professional Antigen-Presenting Cells (APCs) in the context of immune responses.
False
Dendritic cells detach and enter the arterial vessels after processing the antigen at the site of infection.
False
In the endogenous pathway, peptide antigens are produced by processing proteins through ubiquitination.
True
Proteins are marked for degradation by a post-translational modification called phosphorylation in the exogenous pathway.
False
Antigen:MHC I complexes are transported to the cell membrane in the endogenous pathway.
True
The exogenous pathway involves loading peptides into MHC class II in the endoplasmic reticulum.
False
MHC class I α chain associates with the chaperone protein Calreticulin in the antigen presentation process.
False
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.
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.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
