Ch. 48 - The Immune System in Animals

Freeman - Biological Science 8th Edition

Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook

Freeman 8th Edition

Ch. 48 - The Immune System in Animals

Problem 3

Chapter 48, Problem 3

What is the difference between an epitope and an antigen?

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An antigen is a molecule or molecular structure, often a protein or polysaccharide, that can be bound by an antigen-specific antibody or antigen receptor on B and T cells. Antigens are typically foreign substances that enter the body and trigger an immune response.

An epitope, also known as an antigenic determinant, is a specific part of the antigen that is recognized and bound by an antibody. It is a small, specific region on the larger antigen molecule.

While an antigen can have multiple epitopes, each epitope is recognized by a specific antibody. This means that a single antigen can stimulate the production of multiple types of antibodies, each specific to a different epitope.

The distinction between an antigen and an epitope is crucial in understanding how the immune system recognizes and responds to pathogens. Antigens are the targets, and epitopes are the precise points where antibodies attach.

In vaccine development, understanding the specific epitopes on an antigen that provoke a strong immune response can help in designing effective vaccines that target these critical regions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Antigen

An antigen is a substance that can provoke an immune response in the body. Typically, antigens are foreign molecules such as proteins or polysaccharides found on the surface of pathogens like bacteria and viruses. When detected by the immune system, antigens trigger the production of antibodies, which are specific proteins that help neutralize or eliminate the threat.

Epitope

An epitope, also known as an antigenic determinant, is a specific part of an antigen that is recognized by the immune system, particularly by antibodies or T-cell receptors. Epitopes can be linear, consisting of a sequence of amino acids, or conformational, formed by the three-dimensional structure of the antigen. The interaction between epitopes and immune receptors is crucial for the specificity of the immune response.

Immune Response

The immune response is the body's defense mechanism against foreign invaders, such as pathogens. It involves the recognition of antigens and the activation of various immune cells, including B cells and T cells. The immune response can be innate (immediate and non-specific) or adaptive (specific and slower to develop), with the latter providing long-term immunity through memory cells that remember specific epitopes.

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Innate Immune Response

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Textbook Question

What is the primary difference between the innate and adaptive immune responses?

a. The innate immune response does not distinguish between pathogens, while the adaptive immune response does.

b. Only the innate immune response is activated by antigens.

c. The adaptive immune response generates immunological memory and is more specific than the innate immune response.

d. The innate immune response does not kill cells; the adaptive immune response does.

Textbook Question

The overall role of the inflammatory response is to

a. Contain and eliminate foreign cells and material at the site of infection.

b. Increase heat at the site of infection to activate enzymes used in the immune response.

c. Produce antibodies that bind to and eliminate invading cells.

d. Increase blood flow at the site of a wound to flush out invading pathogens.

Textbook Question

What is one of the differences between CD4⁺ and CD8⁺ T cells?

a. CD4⁺ cells are immature, and CD8⁺ cells are mature.

b. CD4⁺ cells are activated, and CD8⁺ cells are not.

c. CD4⁺ cells interact with class II MHC proteins, and CD8⁺ cells interact with class I MHC proteins.

d. CD4⁺ cells activate cell-mediated responses, and CD8⁺ cells activate humoral responses.

Textbook Question

Explain how gene recombination leads to the production of vast numbers of different B-cell receptors.

Textbook Question

What steps are required for most B cells to become fully activated and differentiate into plasma cells?