Genetic location of MHC Major Histocompatibility Complex (MHC) genes are clustered on which chromosomes in humans and in mice, respectively?
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AChromosome 21 in humans, chromosome 6 in mice
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BChromosome 6 in humans, chromosome 21 in mice
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CChromosome 17 in humans, chromosome 6 in mice
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DChromosome 6 in humans, chromosome 17 in mice
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EChromosome 1 in both humans and mice
Answer
Correct Answer: Chromosome 6 in humans, chromosome 17 in mice
Explanation
Introduction / Context:The Major Histocompatibility Complex encodes molecules that present antigenic peptides to T cells and shape immune responses. Knowing the chromosomal location of the MHC is fundamental for genetics, transplantation biology, and disease association studies (HLA typing in humans).
Given Data / Assumptions:
- Human MHC is called HLA (Human Leukocyte Antigen).
- Mouse MHC is called H-2.
- We are asked for chromosomal locations in each species.
Concept / Approach:
The HLA complex resides on human chromosome 6 (short arm, 6p21). The murine H-2 complex is on mouse chromosome 17. These loci are highly polymorphic and include class I (A, B, C in humans), class II (DP, DQ, DR), and class III regions. Their gene products are central to antigen presentation and graft compatibility.
Step-by-Step Solution:
Recall: HLA → human chr 6.Recall: H-2 → mouse chr 17.Match with the option listing 6 (human) and 17 (mouse).Verification / Alternative check:
Standard immunology references and genetic maps place HLA on 6p21 and H-2 on mouse 17, widely used in synteny and QTL studies.
Why Other Options Are Wrong:
- Other chromosome pairings invert or misassign species.
- Chromosome 1 for both species is incorrect for MHC.
Common Pitfalls:
- Confusing numerical chromosome labels between species; remember “6 for HLA, 17 for H-2.”
Final Answer:
Chromosome 6 in humans, chromosome 17 in mice