Microbiology Chapter 15 Flashcards

Questions and Answers

How long after initiation of a primary response do significant amounts of antibody appear in the blood?

10-14 days

Class II MHC molecules are found primarily on?

Macrophages (correct)

T cells

Dendritic cells (correct)

All of the above

Antigens may be processed for presentation by?

Macrophages

B cells

Dendritic cells

All of the above (correct)

What is the definition of clonal selection?

The process in which a lymphocyte's antigen receptor binds to an antigen, allowing the lymphocyte to multiply. Signup and view all the answers

Which of the following contribute to antibody diversity?

All of the above Signup and view all the answers

Why would a person who has their tonsils removed be more susceptible to certain types of infections of the throat and respiratory tract?

Tonsils are secondary lymphoid organs; they help to provide a constant response to the microbes in the oral cavity, helping to keep them in check and preventing them from spreading to other areas. Signup and view all the answers

Which of the following molecules would be expected to be immunogenic?

Serum albumin Signup and view all the answers

Which of the following is the most abundant immunological class produced?

IgA Signup and view all the answers

What would be an appropriate response if an antigen is presented on MHC class II molecules?

An effector CD4 cell activates the presenting cell. Signup and view all the answers

Which is the first antibody class made during the primary response to an antigen?

IgM Signup and view all the answers

How is a T-cell receptor different from a B-cell receptor?

T-cell receptors must have antigen broken down inside a cell and presented to them by a major histocompatibility complex (MHC) molecule. Signup and view all the answers

T cell receptors are identical to antibodies.

False Signup and view all the answers

Please select the correct statement regarding MHC molecules.

Helper T cells recognize antigens presented on MHC class II molecules. Signup and view all the answers

Which class of antibody accounts for most of the circulating antibodies?

IgG Signup and view all the answers

The variable region of an antibody occurs?

on all four chains. Signup and view all the answers

Which of the following antibodies is a pentamer?

IgM Signup and view all the answers

The immunoglobulin monomer consists of?

two heavy and two light chains. Signup and view all the answers

What is a naive lymphocyte?

A lymphocyte that has an antigen receptor but has not yet encountered the antigen recognized by the receptor. Signup and view all the answers

T-independent antigens include?

polysaccharides. Signup and view all the answers

Each class of antibody is specifically defined by its?

amino acid sequence of the constant region of the heavy chain. Signup and view all the answers

Which is the most efficient at initiating the classical pathway of the complement cascade?

IgM Signup and view all the answers

Antibody and antigen are held to one another by covalent bonds.

False Signup and view all the answers

Gene rearrangement is responsible for the generation of the various antibody molecules.

True Signup and view all the answers

It would be useful if antigens were delivered directly to?

Both A and B Signup and view all the answers

T cells are responsible for directly manufacturing antibodies.

False Signup and view all the answers

Would a denatured antigen be expected to have the same epitopes as its native (non-denatured) counterpart? Why?

Yes AND No; SOME epitopes are dependent on 3D conformation (conformational epitopes), while some simply depend on the sequence of amino acids (linear epitopes). Signup and view all the answers

The characteristic function and properties of each class of antibody is determined by the?

constant region on the heavy chains. Signup and view all the answers

CD8 cells are?

T cytotoxic cells. Signup and view all the answers

Only antigen-presenting cells produce MHC class II molecules.

True Signup and view all the answers

The stimulation of B cells to divide and mature is provided by?

T helper cells. Signup and view all the answers

Which of the following does NOT form a memory population after activation and differentiation?

Macrophages Signup and view all the answers

Giant cells are?

used to contain bacterial infections. Signup and view all the answers

Perforin is produced by?

NK cells. Signup and view all the answers

T cells mature in the?

thymus. Signup and view all the answers

All antigens are immunogens.

False Signup and view all the answers

The scientist who received the first Nobel Prize in Medicine for his work on antibody therapy was?

von Behring. Signup and view all the answers

The immune response is directed against an entire molecule.

False Signup and view all the answers

Which of the following do not induce a strong immune response?

Both A and B Signup and view all the answers

The only class of antibody that can cross the placenta is __________.

IgG Signup and view all the answers

The immunoglobulin that is important in hypersensitivity reactions is __________.

IgE Signup and view all the answers

Which of the following is/are a(n) antigen-presenting cell(s)?

All of the above Signup and view all the answers

Macrophages, dendritic cells, AND B cells?

T helper cells. Signup and view all the answers

Which of the following class of antibody is primarily found in external secretions?

IgA Signup and view all the answers

Ag-Ab binding may result in all of the following EXCEPT?

Fever Signup and view all the answers

The peptides presented by MHC class II peptide molecules are?

exogenous antigens. Signup and view all the answers

Which of the following is/are secondary lymphoid organ(s)?

Both C and D Signup and view all the answers

Antibody molecules are very rigid in structure.

False Signup and view all the answers

The function of the secretory component of the IgA molecule is?

to protect IgA from being destroyed by proteolytic enzymes. Signup and view all the answers

Macrophages and dendritic cells are?

antigen-presenting cells. Signup and view all the answers

What happens when a helper T cell is activated?

Two populations of cells are formed: memory TH cells and effector TH cells; the effector TH cells play a role in activating B cells. Signup and view all the answers

Please identify the incorrect definition.

MHC class II—molecules that present antigen to cytotoxic T cells Signup and view all the answers

The cells that actually secrete antibodies are?

plasma cells. Signup and view all the answers

Identify the role(s) of natural killer cells.

All of the above Signup and view all the answers

The chains of an antibody molecule are bonded to one another by?

disulfide bonds. Signup and view all the answers

In opsonization with IgG, why would it be important that IgG reacts with the antigen BEFORE a phagocytic cell recognizes the antibody molecule?

If the IgG is bound to the phagocyte BEFORE opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen. Signup and view all the answers

IgA is the most abundant immunoglobulin made by the body.

True Signup and view all the answers

The best possible analogy available for the way in which variable (V), diversity (D), and joining (J) antibody gene segments are put together is?

to think of the various segments as a bingo game. Signup and view all the answers

According to the clonal selection theory, each B cell is already programmed to produce a specific antibody.

true Signup and view all the answers

How is the central portion of a T cell receptor complex functionally analogous to the center of the B cell receptor complex?

Both receptors bind epitopes (small amino acid sections of antigen molecules). Signup and view all the answers

Apoptosis is a form of programmed cell death and is induced in target cells by effector T cytotoxic cells.

true Signup and view all the answers

T cells and B cells are produced in the?

bone marrow. Signup and view all the answers

A term synonymous with antibody is?

immunoglobulin. Signup and view all the answers

Antigens interact with antibodies at?

the outer end of each arm of the Y. Signup and view all the answers

Which is the most efficient at initiating the classical pathway of the complement cascade?

IgM Signup and view all the answers

Antigens may be processed for presentation by?

All of the above Signup and view all the answers

CD4 cells are also known as?

T helper cells. Signup and view all the answers

Which of the following is not typical of an antigen?

Low molecular weight Signup and view all the answers

T-independent antigens can activate B cells directly.

True Signup and view all the answers

CD8 cells are?

T cytotoxic cells. Signup and view all the answers

An IgG molecule has two?

heavy chains, light chains AND antigen binding sites. Signup and view all the answers

T cell receptors are identical to antibodies.

False Signup and view all the answers

Cytotoxic T cells primarily are responsible for?

cell-mediated immunity. Signup and view all the answers

Secondary lymphoid organs?

facilitate interactions between cells. Signup and view all the answers

The surface receptors on B and T cells both?

have variable and constant regions. Signup and view all the answers

'Clonal selection' and 'clonal expansion'

All of the answer choices are correct. Signup and view all the answers

Specific regions on an antigen molecule to which the immune response is directed are?

antigenic determinants. Signup and view all the answers

Antibodies are made by?

B cells/plasma cells. Signup and view all the answers

Epitopes or antigenic determinants?

are parts of an antigen recognized by an antibody. Signup and view all the answers

Study Notes

Antibody Response

Significant amounts of antibody appear in the blood 10-14 days after the initiation of a primary response.
The first antibody class produced during a primary response to an antigen is IgM.
The most abundant immunological class produced is IgA.

Major Histocompatibility Complex (MHC)

Class II MHC molecules are primarily found on macrophages and dendritic cells.
Helper T cells recognize antigens presented on MHC class II molecules; only antigen-presenting cells produce MHC class II molecules.

Clonal Selection and Diversity

Clonal selection is the process where a lymphocyte's antigen receptor binds to an antigen, triggering lymphocyte multiplication.
Antibody diversity is generated through gene rearrangement, imprecise joining, and combinatorial associations.

Antigens and Immunogens

Antigens are processed for presentation by macrophages, B cells, and dendritic cells.
T-independent antigens include polysaccharides; they can activate B cells directly.
Not all antigens are immunogens; only those that elicit an immune response are considered immunogenic.

Antibody Structure and Function

Antibody molecules consist of two heavy and two light chains, with the variable region on all four chains.
The binding of antibodies to antigens occurs at the outer end of each arm of the Y-shaped molecule.
IgM is the most efficient class of antibody at initiating the classical pathway of the complement cascade.

Cellular Immunity

T cell receptors differ from B cell receptors, as they require the antigen to be presented by MHC molecules.
CD8 cells are classified as T cytotoxic cells, while CD4 cells are known as T helper cells.
Cytotoxic T cells primarily mediate cell-mediated immunity.

Lymphocyte Activation

Activation of T helper cells leads to the formation of memory and effector populations; effector T cells activate B cells.
Plasma cells are the cells that secrete antibodies.

Immune Response Mechanisms

Opsonization involves IgG reacting with antigens before phagocytic cells recognize the antibodies.
Natural killer cells engage in antibody-dependent cellular cytotoxicity and regulate certain immune responses.
The secretory component of IgA protects it from degradation by proteolytic enzymes.

Secondary Lymphoid Organs

Secondary lymphoid organs, such as the spleen and lymph nodes, facilitate interactions between immune cells.
Tonsils are secondary lymphoid organs that help maintain oral cavity microbial balance.

Epitopes and Antigen Recognition

Epitopes, or antigenic determinants, are specific regions on an antigen to which antibodies bind.
Some epitopes are linear and depend on amino acid sequence, while others are conformational and depend on the 3D structure of the antigen.

Additional Key Points

Gene rearrangement enables the diversity of antibody molecules.
Antibody and antigen interactions are held together by non-covalent bonds, while chains of antibodies are linked by disulfide bonds.
The immunoglobulin molecule important in hypersensitivity reactions is IgE, while IgG is the only class that can cross the placenta.

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Description

This quiz covers essential concepts from Chapter 15 of Microbiology. Test your knowledge on topics such as antibody response times, MHC molecules, and antigen processing. Utilize these flashcards for efficient study and review.