This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Immunoglobulins”.
1. Synthesis of antibodies takes place by which of the following cells?
a) Bone marrow cells
b) T-cells
c) B-cells
d) Lymph
View Answer
Explanation: Antibodies are also called immunoglobulin, the antigen- binding glycoproteins, which are exclusively synthesized by B-cells and in billions of forms with different amino acid sequences and different antigen binding sites.
2. The basic structure of antibodies are______
a) Y-shaped
b) X-shaped
c) Linear
d) Hyperbolic
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Explanation: The simple antibody structure has two identical antigen-binding sites forming a Y-shaped molecule. These antigen-binding sites are present on the tip of each arm of the Y.
3. Name the heavy chain of immunoglobulin G.
a) μ
b) ε
c) α
d) γ
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Explanation: Immunoglobulin has five isotopes with different heavy chains, i.e. IgM has a μ heavy chain, IgE has ε, IgA has α, and IgG has a γ heavy chain.
4. What is the name of the hypervariable region of immunoglobin, which is responsible for its diversity?
a) CDR
b) Hinge region
c) Epitope
d) Agretope
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Explanation: CDR is complementarity determining regions which impart the diversity in the variable region of both heavy and light chains. These are three small hypervariable regions and remaining part is called framework region.
5. Who discovered the structure of immunoglobulin by treating it with beta-mercaptoethanol?
a) Nisonoff
b) Edelman
c) Porter
d) Whittekar
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Explanation: Edelman discovered that when immunoglobulin treated with beta-mercaptoethanol, it will fall apart into four chains, i.e. two identical light chain and two large heavy chains. This result was considered to propose a structure of immunoglobulin.
6. Which of the following amino acid is found in the hinge region?
a) Alanine
b) Aspargine
c) Proline and cysteine
d) Phenylalanine
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Explanation: Hinge region is found in IgG, IgA, and IgD to provide flexibility in its structure. These regions are rich in proline and cysteine and basically found between two Fab arms of the Y-shaped antibody.
7. Which immunoglobulin can pass through placenta?
a) IgD
b) IgE
c) IgM
d) IgG
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Explanation: IgG is the only antibody which can pass through the placenta, except IgG2 all other subtypes of IgG can cross the placenta and transfer immunity from mother to fetus.
8. Name the class of immunoglobulin which has a pentameric structure?
a) IgE
b) IgG
c) IgA
d) IgM
View Answer
Explanation: IgM is the first antibody to produce during the primary response to antigen and it is also the first antibody which is made by the developing B-cells. It is composed of five units and formed pentameric structure with a J-chain.
9. Which of these immunoglobulins is present in external secretion?
a) IgG
b) IgM
c) IgA
d) IgE
View Answer
Explanation: IgA is the predominant immunoglobulin which is present in the external secretion such as saliva, breast feed, tears, and mucus. It constitutes 10-15% of total immunoglobin in serum.
10. Name the class of immunoglobulin which takes part in hypersensitivity reaction?
a) IgG
b) IgE
c) IgA
d) IgM
View Answer
Explanation: IgE mediates hypersensitivity reaction which is responsible for the symptoms of hay fever, asthma, and anaphylactic shock. It includes degranulation of basophils and mast cells.
Sanfoundry Global Education & Learning Series – Life Sciences.
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