MIMG C185A Final Exam |
Questions and Answers | 2025
Revised Update | 100% Correct -
UCLA.
SECTION 1: MHC STRUCTURE AND
Question 1
An inbred (syngeneic) strain of mice has the following MHC locus organization: K,
I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. How many different types of MHC I molecules will
these mice express on the surface of their antigen-presenting cells (APCs)?
A) 2
B) 4
C) 6
D) 8
E) 9
,Correct Answer: D
Rationale: The MHC locus shows 9 genes total: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. The L gene
is duplicated. Since the mice are inbred, both maternal and paternal MHC I genes are the
same. However, the duplicated L gene produces two identical proteins that are not distinct,
so only 8 different MHC I molecules are expressed.
Question 2
For the same inbred mice described above, how many different types of MHC II
molecules will be expressed on the surface of APCs?
A) 0
B) 2
C) 3
D) 4
E) 6
Correct Answer: A
Rationale: The alpha and beta chains available cannot recombine with each other. I-Aα is
only compatible with I-Aβ, and I-Eβ is only compatible with I-Eα. These mice lack I-Eα
entirely, so no functional MHC II complexes can form.
Question 3
Westwood mice are genetically manipulated and cannot produce TAP1 and TAP2
proteins in any of their cells. What type of microorganisms will these animals be
susceptible to?
A) Extracellular bacteria only
B) Extracellular parasites only
C) Intracellular pathogens (viruses, intracellular bacteria)
D) Both extracellular and intracellular pathogens
E) None, they have normal immunity
,Correct Answer: C
Rationale: TAP proteins are required for transporting peptides from the cytosol into the
endoplasmic reticulum for loading onto MHC class I molecules. Without functional TAP,
MHC I cannot be expressed, and CD8+ T cells cannot recognize intracellular pathogens.
Question 4
Which of the following MHC gene products could be expressed in F1 progeny of
an inbred UCLA (K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L) strain crossed with Westwood (K,
I-Aα, I-Aβ, I-Eα, I-Eβ, D, L) strain?
A) Only MHC I from UCLA and MHC II from Westwood
B) MHC I from both parents; MHC II from Westwood only
C) MHC I from UCLA only; MHC II from Westwood only
D) MHC I from UCLA only; MHC II from both parents
E) MHC I and MHC II from both parents
Correct Answer: E
Rationale: The F1 hybrid mice will inherit MHC genes from both parents. Since both strains
are inbred, all F1 progeny will be heterozygous and express MHC I and MHC II genes from
both parental strains. Both strains express functional MHC I. Westwood provides functional
MHC II.
Question 5
When the UCLA strain is crossed with Westwood strain, how many different types
of MHC II molecules will be expressed?
A) 0
B) 1
C) 2
D) 3
E) 4
, Correct Answer: D
Rationale: The UCLA strain does not express MHC II. However, the Westwood strain has
both alpha and beta chains for both I-A and I-E. The hybrid will express MHC II due to this
contribution. Three different types of MHC II will be expressed (one I-A and two I-E).
Question 6
Will the UCLA/Westwood hybrid mice have normal immune responses?
A) Yes, because they have functional MHC I and MHC II complexes
B) No, because TAP is nonfunctional
C) No, because MHC II is still missing
D) Only against extracellular pathogens
E) Only against intracellular pathogens
Correct Answer: A
Rationale: The hybrid mice have functional MHC I (from UCLA inheritance) and functional
MHC II (from Westwood inheritance). Both CD4+ and CD8+ T cells can perform their
immune functions, so the mice will have normal immune responses.
Question 7
Which of the following cells is NOT a professional antigen-presenting cell (APC)?
A) Dendritic cell
B) Macrophage
C) B lymphocyte
D) Neutrophil
Correct Answer: D
Rationale: Professional APCs (dendritic cells, macrophages, B cells) express MHC class II
and co-stimulatory molecules (CD80/CD86) to activate naïve T cells. Neutrophils do not
primarily function as APCs.
Questions and Answers | 2025
Revised Update | 100% Correct -
UCLA.
SECTION 1: MHC STRUCTURE AND
Question 1
An inbred (syngeneic) strain of mice has the following MHC locus organization: K,
I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. How many different types of MHC I molecules will
these mice express on the surface of their antigen-presenting cells (APCs)?
A) 2
B) 4
C) 6
D) 8
E) 9
,Correct Answer: D
Rationale: The MHC locus shows 9 genes total: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. The L gene
is duplicated. Since the mice are inbred, both maternal and paternal MHC I genes are the
same. However, the duplicated L gene produces two identical proteins that are not distinct,
so only 8 different MHC I molecules are expressed.
Question 2
For the same inbred mice described above, how many different types of MHC II
molecules will be expressed on the surface of APCs?
A) 0
B) 2
C) 3
D) 4
E) 6
Correct Answer: A
Rationale: The alpha and beta chains available cannot recombine with each other. I-Aα is
only compatible with I-Aβ, and I-Eβ is only compatible with I-Eα. These mice lack I-Eα
entirely, so no functional MHC II complexes can form.
Question 3
Westwood mice are genetically manipulated and cannot produce TAP1 and TAP2
proteins in any of their cells. What type of microorganisms will these animals be
susceptible to?
A) Extracellular bacteria only
B) Extracellular parasites only
C) Intracellular pathogens (viruses, intracellular bacteria)
D) Both extracellular and intracellular pathogens
E) None, they have normal immunity
,Correct Answer: C
Rationale: TAP proteins are required for transporting peptides from the cytosol into the
endoplasmic reticulum for loading onto MHC class I molecules. Without functional TAP,
MHC I cannot be expressed, and CD8+ T cells cannot recognize intracellular pathogens.
Question 4
Which of the following MHC gene products could be expressed in F1 progeny of
an inbred UCLA (K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L) strain crossed with Westwood (K,
I-Aα, I-Aβ, I-Eα, I-Eβ, D, L) strain?
A) Only MHC I from UCLA and MHC II from Westwood
B) MHC I from both parents; MHC II from Westwood only
C) MHC I from UCLA only; MHC II from Westwood only
D) MHC I from UCLA only; MHC II from both parents
E) MHC I and MHC II from both parents
Correct Answer: E
Rationale: The F1 hybrid mice will inherit MHC genes from both parents. Since both strains
are inbred, all F1 progeny will be heterozygous and express MHC I and MHC II genes from
both parental strains. Both strains express functional MHC I. Westwood provides functional
MHC II.
Question 5
When the UCLA strain is crossed with Westwood strain, how many different types
of MHC II molecules will be expressed?
A) 0
B) 1
C) 2
D) 3
E) 4
, Correct Answer: D
Rationale: The UCLA strain does not express MHC II. However, the Westwood strain has
both alpha and beta chains for both I-A and I-E. The hybrid will express MHC II due to this
contribution. Three different types of MHC II will be expressed (one I-A and two I-E).
Question 6
Will the UCLA/Westwood hybrid mice have normal immune responses?
A) Yes, because they have functional MHC I and MHC II complexes
B) No, because TAP is nonfunctional
C) No, because MHC II is still missing
D) Only against extracellular pathogens
E) Only against intracellular pathogens
Correct Answer: A
Rationale: The hybrid mice have functional MHC I (from UCLA inheritance) and functional
MHC II (from Westwood inheritance). Both CD4+ and CD8+ T cells can perform their
immune functions, so the mice will have normal immune responses.
Question 7
Which of the following cells is NOT a professional antigen-presenting cell (APC)?
A) Dendritic cell
B) Macrophage
C) B lymphocyte
D) Neutrophil
Correct Answer: D
Rationale: Professional APCs (dendritic cells, macrophages, B cells) express MHC class II
and co-stimulatory molecules (CD80/CD86) to activate naïve T cells. Neutrophils do not
primarily function as APCs.
