Chapter 13, Problem 1Q

A single bacterium has _______ epitope(s).

1. a. a specific
2. b. multiple
3. c. MHC
4. d. clonal

Summary Introduction

Introduction:

The capacity of a lymphocyte to distinguish the difference between molecular shapes is so sensitive that it can recognize and respond to only a specific portion of an antigenic molecule. This fragment of the molecule is known as an epitope.

Answer to Problem 1Q

Correct answer:

A single bacterium has multiple epitopes. Therefore, option (b) is correct.

Option (b) is given as “multiple”.

Explanation of Solution

Justify the reason for the correct statement:

The epitope is an antigenic determinant fragment of an antigenic molecule. This is recognized by the immune system. It is the specific portion of antigen molecules and a single antigenic molecule carries multiple epitopes. Paratope is the portion of an antibody that binds to the antigenic epitope and trigger an immune response such as phagocytosis.

Hence, option (b) is correct.

Justify the reasons for the incorrect statements:

Option (a) is given as “a specific”.

Many epitopes are present on antigen molecules that generate specific immunity. Hence, it is a wrong answer.

Option (c) is given as “MHC”.

MHC stands for “major histocompatibility complex”. It is a surface marker that helps presentation of the pathogenic epitope to the T-cells. Hence, it is a wrong answer.

Option (d) is given as “clonal”.

Foreign antigen activates B or T cells that are appropriate (correct) for it by the mechanism of clonal selection. Hence, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.

Conclusion

Multiple epitopes are found on a single bacterium.