Question 16:
An antigenic determinant to which a given antibody binds is called:
Antigenic Determinant Antibody Binding
An antigenic determinant is the specific region on an antigen where an antibody binds. The correct term is epitope, making option (C) right.
Correct Answer
(C) Epitope
Epitope refers to the precise part of an antigen recognized and bound by an antibody’s paratope.
Term Definitions
Epitopes are small sites, often 5-8 amino acids or sugars, on antigens that antibodies target specifically. They drive immune recognition, with conformational epitopes relying on 3D structure and linear ones on sequence.
Option Analysis
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(A) Epimer: Stereoisomers differing at one chiral carbon; relevant in carbohydrate chemistry, not immunology.
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(B) Cytokine: Signaling proteins like interleukins that regulate immune cells; they do not bind antigens.
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(C) Epitope: Correct; the antigenic determinant antibodies bind for immune response activation.
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(D) Anticodon: tRNA triplet base-pairing with mRNA codons in translation; unrelated to antibodies.
| Option | Term | Role | Status |
|---|---|---|---|
| A | Epimer | Sugar isomer | Wrong |
| B | Cytokine | Immune signaler | Wrong |
| C | Epitope | Antibody binding site | Correct |
| D | Anticodon | Translation matcher | Wrong |
Exam Preparation Tips
Link “epitope” to “epi” (upon) + “tope” (place); memorize via antibody-antigen fit analogy. Common distractors test biochemistry vs. immunology concepts.
