This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Major Histocompatibility Complex”.
1. Major Histocompatibility Complex is a tight cluster of linked___________
d) Lipid molecules
Explanation: MHC is polygenic in nature, i.e. several genes control the expression of the MHC molecule. These are cell surface proteins which are present with peptide on antigen presenting cells.
2. What is the name of MHC in humans?
Explanation: Genes for MHC are located on the short arm of chromosome 6 in humans. In human, it is also known as human leukocyte antigens (HLA). MHC is glycoproteins which are expressed on all nucleated cells.
3. All the individual of the same species has the same allele of MHC genes.
Explanation: MHC is polymorphic in nature and shows genetic polymorphism by expressing different alleles of a gene. Different individuals have different types of MHC genes. MHC genes are expressed as codominantly.
4. Which of the following polypeptide is important for the expression of MHC I on the cell membrane?
Explanation: β2-microglobin is encoded by chromosome 15, it is always attached to α3 subunit of MHC I molecules through non-covalent interactions. It does not have a tail.
5. Which of these are non-professional antigen presenting cells?
b) Dendritic cells
d) B lymphocytes
Explanation: Antigen presenting cells (APC) is of two types i.e. professional and non-professional antigen presenting cells. Professional antigen presenting cells are B-lymphocytes, dendritic cells, and macrophages while non-professional APCs are fibroblast, epithelial cells, glial cells etc.
6. Name the cell which receives antigen presented by MHC molecule.
a) Nk cells
Explanation: MHC molecules present processed antigen to T-cells as T-cell receptor does not recognize free antigen, it will recognize only those antigens which are bound to MHC molecules.
7. Name the class of MHC which is recognized by CD4 TH cell.
a) MHC cannot recognize T cells
b) MHC III
c) MHC I
d) MHC II
Explanation: CD4 is a monomeric single chain which recognizes MHC II molecule and is present on T helper cell. It consists of a core extracellular domain and has three critical serine residues on a cytoplasmic tail.
8. Which MHC molecule recognizes CD8 TC cells?
a) MHC I
b) MHC II
c) MHC III
Explanation: CD8 is a co-receptor of T-cell and is present on the T cytosolic cell. It is a hetrodimer of α and β chains and recognizes MHC I molecule.
9. Name the part of processed antigen that binds to the MHC molecule and recognized by T-cells?
Explanation: Agretope is the part of processed antigen that is attached to MHC molecule and exposed to T-cell.
10. Which of the following statement is INCORRECT about superantigens?
a) Viral or bacterial proteins
b) Endogenous by nature
c) Unique binding ability
d) Activate a large number of T-cells
Explanation: Superantigens are viral or bacterial proteins which have the unique binding ability of T-cell receptor and MHC II molecules, i.e. it binds simultaneously to both and activate large numbers of T-cells. It can be both either endogenous or exogenous in nature.
Sanfoundry Global Education & Learning Series – Life Sciences.
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