Immunology Quiz- Introduction To Antigen Recognition
Questions and Answers
- 1.
Which of the following is NOT true regarding the complement system?
- A.
They are serum proteins that form protein cascades, each activated component activating the next to generate a physiologic response
- B.
They can bind to bacteria, making holes in their membrane
- C.
They attract phagocytes to both foreign material and self cells
- D.
Binding of MBLs to a bacterial capsule triggers the complement cascade
- E.
They help to eliminate immune complexes (antibody-antigen) and prevent them from damaging the body
Correct Answer
C. They attract phagocytes to both foreign material and self cellsExplanation
The complement system is a group of serum proteins that work together to form protein cascades, where each activated component activates the next in order to generate a physiologic response. These proteins can bind to bacteria and create holes in their membrane, which leads to bacterial lysis. They also help to eliminate immune complexes and prevent them from causing damage to the body. However, the statement that they attract phagocytes to both foreign material and self cells is not true. Phagocytes are attracted to foreign material, such as bacteria or other pathogens, but not self cells.Rate this question:
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- 2.
Which of the following key components of the complement pathway can be activated by the lectin, classical, and alternative pathways?
- A.
C1
- B.
C3
- C.
C5
- D.
C7
- E.
C9
Correct Answer
B. C3Explanation
C3 is the correct answer because it is a key component that can be activated by all three pathways of the complement system: the lectin, classical, and alternative pathways. C3 activation is a crucial step in the complement cascade, leading to the formation of the membrane attack complex (MAC) and subsequent destruction of pathogens. Activation of C3 initiates a series of events that amplify the immune response and enhance the ability of the immune system to eliminate foreign invaders.Rate this question:
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- 3.
Match the three types of molecules that recognize antigen with their description: Can create a soluble antigen receptor (antibody)
- A.
B cell receptor (BCR)
- B.
T cell receptor (TCR)
- C.
Major histocompatibility complex (MHC)
Correct Answer
A. B cell receptor (BCR)Explanation
The B cell receptor (BCR) is a molecule that recognizes antigens and can create a soluble antigen receptor, also known as an antibody. B cells are a type of white blood cell that produces antibodies to help the immune system defend against pathogens. The BCR is located on the surface of B cells and is responsible for binding to specific antigens. When the BCR recognizes an antigen, it triggers the B cell to produce and release antibodies that can neutralize or eliminate the antigen.Rate this question:
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- 4.
Match the three types of molecules that recognize antigen with their description: Recognize antigens bound to MHC
- A.
B cell receptor (BCR)
- B.
T cell receptor (TCR)
- C.
Major histocompatibility complex (MHC)
Correct Answer
B. T cell receptor (TCR)Explanation
The T cell receptor (TCR) is the molecule that recognizes antigens bound to the major histocompatibility complex (MHC). MHC molecules are found on the surface of cells and present antigens to T cells. The TCR specifically binds to the antigen-MHC complex, allowing T cells to recognize and respond to foreign substances. The B cell receptor (BCR) is responsible for recognizing antigens directly without the need for MHC presentation.Rate this question:
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- 5.
Match the three types of molecules that recognize antigen with their description: A cluster of genes that encode proteins
- A.
B cell receptor (BCR)
- B.
T cell receptor (TCR)
- C.
Major histocompatibility complex (MHC)
Correct Answer
C. Major histocompatibility complex (MHC)Explanation
The Major histocompatibility complex (MHC) is a cluster of genes that encode proteins. These proteins are responsible for presenting antigens to T cells, which play a crucial role in the immune response. The MHC molecules bind to antigens and display them on the surface of cells, allowing T cells to recognize and respond to the antigens. B cell receptors (BCRs) and T cell receptors (TCRs) are not involved in encoding proteins or presenting antigens, making them incorrect choices for this description.Rate this question:
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- 6.
The genes encoding which of the following can undergo hypermutation to create receptors that are an even better fit for foreign antigens?
- A.
BCRs
- B.
TCRs
- C.
MHCs
- D.
BCRs & TCRs
- E.
BCRs, TCRs, & MHCs
Correct Answer
A. BCRsExplanation
BCRs (B cell receptors) can undergo hypermutation to create receptors that are an even better fit for foreign antigens. This process is known as somatic hypermutation and it occurs in the variable region of the BCR gene. Through somatic hypermutation, B cells can generate a diverse repertoire of BCRs that have a higher affinity for specific antigens, allowing for a more effective immune response. TCRs (T cell receptors) and MHCs (major histocompatibility complexes) do not undergo hypermutation in the same way as BCRs.Rate this question:
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- 7.
Which of the following has an immunoglobulin fold?
- A.
BCRs
- B.
TCRs
- C.
MHCs
- D.
BCRs & TCRs
- E.
BCRs, TCRs, & MHCs
Correct Answer
D. BCRs & TCRsExplanation
BCRs (B cell receptors) and TCRs (T cell receptors) have an immunoglobulin fold. The immunoglobulin fold is a characteristic structural motif found in antibodies and other proteins involved in immune responses. It consists of a series of beta strands connected by loops, forming a sandwich-like structure. BCRs and TCRs play a crucial role in recognizing and binding to antigens, initiating immune responses. The presence of the immunoglobulin fold in BCRs and TCRs allows them to bind to specific antigens and activate immune cells. MHCs (major histocompatibility complexes) do not have an immunoglobulin fold, which is why they are not included in the correct answer.Rate this question:
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- 8.
The genes encoding which of the following are extensively polymorphic (have multiple alleles or forms of the same gene)?
- A.
BCRs
- B.
TCRs
- C.
MHCs
- D.
BCRs & TCRs
- E.
BCRs, TCRs, & MHCs
Correct Answer
C. MHCsExplanation
MHCs, or major histocompatibility complexes, are extensively polymorphic. This means that they have multiple alleles or forms of the same gene. The MHC genes play a crucial role in the immune system by encoding proteins that present antigens to T cells, allowing the immune system to recognize and respond to foreign substances. The high level of polymorphism in MHC genes ensures a diverse range of antigen presentation, increasing the likelihood of an effective immune response against a wide variety of pathogens.Rate this question:
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- 9.
What types of cell is class I MHC found on?
- A.
B cells
- B.
Macrophages
- C.
Dendritic cells
- D.
Essentially all cells
- E.
Mainly on A, B, & C
Correct Answer
D. Essentially all cellsExplanation
Class I MHC molecules are found on essentially all cells. Class I MHC molecules are involved in presenting antigens to cytotoxic T cells, which play a crucial role in immune responses against intracellular pathogens such as viruses and some bacteria. Since all nucleated cells have the potential to be infected by intracellular pathogens, they express class I MHC molecules to present antigens derived from these pathogens to cytotoxic T cells. This allows the immune system to recognize and eliminate infected cells. Therefore, class I MHC molecules are found on essentially all cells.Rate this question:
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- 10.
What types of cell is class II MHC found on?
- A.
B cells
- B.
Macrophages
- C.
Dendritic cells
- D.
Essentially all cells
- E.
Mainly on A, B, & C
Correct Answer
E. Mainly on A, B, & CExplanation
Class II MHC molecules are primarily found on antigen-presenting cells such as B cells, macrophages, and dendritic cells. These cells play a crucial role in the immune response by presenting antigens to helper T cells. This interaction is important for the activation of the adaptive immune system and the production of specific immune responses against pathogens. While class II MHC molecules can also be found on other cell types, their presence on A, B, and C cells is particularly significant for antigen presentation and immune regulation.Rate this question:
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- 11.
What is the function of major histocompatibility complex (MHC) molecules?
- A.
Present sugars to T cells
- B.
Present peptides to T cells
- C.
Create holes in the membranes of bacteria
- D.
Lyse foreign antigens
- E.
Phagocytize foreign antigens
Correct Answer
B. Present peptides to T cellsExplanation
The major histocompatibility complex (MHC) molecules play a crucial role in the immune system by presenting peptides to T cells. This presentation allows T cells to recognize and respond to foreign antigens, initiating an immune response. By presenting peptides, MHC molecules help T cells identify infected or abnormal cells, leading to the activation of the immune system to eliminate the threat. This function of MHC molecules is essential for immune surveillance and defense against pathogens.Rate this question:
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- 12.
Unlike B cell receptors (BCRs), T cell receptors (TCRs) can only recognize foreign antigen if it is presented as a complex with a MHC molecule.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
T cell receptors (TCRs) are only able to recognize foreign antigens if they are presented as a complex with a major histocompatibility complex (MHC) molecule. This is in contrast to B cell receptors (BCRs), which can directly recognize antigens without the need for MHC presentation. Therefore, the statement that TCRs can only recognize foreign antigen when presented with an MHC molecule is true.Rate this question:
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- 13.
If the structure of an individuals MHC molecules makes it impossible for them to recognize and bind any peptide antigen from a given virus, that individual will still be able to activate a T cell response to cells infected with that virus.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
If the structure of an individual's MHC molecules does not allow them to recognize and bind any peptide antigen from a specific virus, it means that the individual's immune system will not be able to directly target and eliminate the virus-infected cells. However, T cells can still be activated by other means, such as through the presentation of viral antigens by other cells or through the recognition of other viral proteins. Therefore, even if the individual's MHC molecules cannot directly bind the viral antigens, they can still activate a T cell response to cells infected with that virus.Rate this question:
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- 14.
Which of the following is NOT true about MHC molecules but true about B and T cells?
- A.
The genes that encode molecules are the most variable genes we know of in the human genome (polygenic)
- B.
They are extensively polymorphic (existence of multiple alleles or forms of the same gene)
- C.
Every cell in each individual expresses the same set of molecules
- D.
) Every cell expresses a different molecule created from multiple gene segments that undergo somatic rearrangement
- E.
Their diversity exists in the population as a whole, not in the individual
Correct Answer
D. ) Every cell expresses a different molecule created from multiple gene segments that undergo somatic rearrangementExplanation
MHC molecules are not expressed by every cell in the body. Instead, they are only expressed on the surface of certain cells, such as antigen-presenting cells. B and T cells, on the other hand, do express a different molecule created from multiple gene segments that undergo somatic rearrangement. This process allows for the generation of a diverse repertoire of B and T cell receptors, which is important for recognizing and responding to a wide range of pathogens. The other options are incorrect because MHC molecules are indeed highly variable and polymorphic, and their diversity exists in the individual, not just the population as a whole.Rate this question:
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- 15.
Given that an individual’s parents have completely different HLA genes, that individual will have about____ different class I and II MHC molecules on the surface of certain of their lymphoid cells.
- A.
3
- B.
6
- C.
9
- D.
12
- E.
15
Correct Answer
D. 12Explanation
An individual will have about 12 different class I and II MHC molecules on the surface of certain lymphoid cells if their parents have completely different HLA genes. This is because each parent contributes half of their HLA genes to their offspring, resulting in a combination of different MHC molecules. Since there are multiple alleles for both class I and II MHC genes, the individual will have approximately 12 different combinations of these molecules.Rate this question:
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Aug 22, 2023Quiz Edited by
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May 11, 2011Quiz Created by
Smb6
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