BIOL 400 Ch. 33
When gene segment combination is taking place for production of antibody genes, the constant region (C) segments ______ put together with the other segments before transcription is used to form the corresponding RNA molecule.
are not
When antibodies or lymphocytes produced by one host are harvested and administered to another organism to provide it with temporary protection against a pathogen/infection, it is an example of ______ immunity.
artificially acquired passive
Select three cell types that express class II MHC molecules on their surface.
macrophages mature B cells dendritic cells
Like innate immunity, adaptive immunity must differentiate between self and non-self; however, this recognition of non-self by adaptive immunity is ______ than that of innate immunity.
more specific
Attempting to "match" donor tissues with those of the recipient helps prevent rejection due to less stimulation of recipient immune responses against donor cell _____ molecules. (use acronym)
MHC
Class II MHC molecules are required for communication between "antigen presenting cells" (macrophages, dendritic cells, and B cells) and what type of cell?
T cells
Bacterial LPS and certain tumor-promoting agents are good examples of ______.
T-independent antigens
Combinatorial joining in B cells occurs when ______.
antibody gene segments are joined together at the DNA level before being expressed
The two main arms (or branches) of adaptive immunity are cell-mediated immunity and _____ immunity
antibody mediated
The _____ term refers to any substance (either self or nonself) that induces an immune response.
antigen
T cells have T-cell receptor complexes on their surface that bind to what type of molecules on the surface of other cells?
antigen fragments presented by MHC molecules
Select three correct descriptions of human IgE.
most is tightly bound by Fc receptors on mast cells/basophils includes skin-sensitizing and anaphylactic antibodies very low levels in serum
When an individual acquires an infection that induces the immune system to produce a protective response, it is an example of which type of active immunity?
naturally acquired active immunity
Which antibody class accounts for 80% of the antibodies in human serum?
lgG
Which immunoglobulin type is the first antibody produced during B cell maturation?
lgM
Activation of a naive, mature CD8+ T cell causes it to differentiate into a CTL, or cytotoxic T _____
lymphocyte
The general term for an inactivated bacterial toxin used as a vaccine is a(n) _____
toxoid
Arrange the four components of clonal selection according to the most logical order in which they occur.
(1) a pool of lymphocytes is generated, which includes cells capable of binding to a very large number of possible epitopes. (2) self-reactive cells are eliminated to prevent auto reactivity (response to self) (3) when lymphocytes are exposed to their specific antigen, they proliferate, forming identical clones (4) all clonal cells can react to the original stimulating epitope.
Match each type of B cell with the best description. (1) memory B cell (2) naive B cell (3) plasma cell
(1) has differentiated into a cell that responds more quickly to its specific antigen should it be encountered again in the future (2) a mature B cell that has not yet been activated by its specific antigenic epitope (3) has differentiated into a cell specialized for antibody production making large amounts of its specific single type of antibody
Arrange these steps in T-dependent antigen activation of a B cell in chronological order, with the earliest step at the top.
1. B cell binds to specific antigen via its BCR, then internalizesm processes, and presents fragments of antigen on class II MHC molecules2. T-helper cell associates with a B cell displaying a specific antigen frangment/ class II MHX complex3. T-helper cell secretes B cll growth factors4. B cell proliferates and differentiated into a plasma cell5. plasma cell secretes antibodies
Antibody class switching is the process by which ______.
B cells differentiate into plasma cells that secrete antibody belonging to a different class than originally produced
Which two enzymes are required for generating antibody diversity by combinatorial joining in developing B cells?
RAG-1 and RAG-2
Exogenous antigen processing allows class II MHC molecules to present peptide fragments to what type of cell?
CD4+ T-helper cells
The recombination events required for antibody class switching take place at the ______ level.
DNA
Which part of an antibody molecule binds to a specific epitope of an antigen?
Fab
Match each part of an immunoglobulin molecule with its unique role.
Fab region- binds to a specific antigen Fc region- binds to receptors on various cells or activates complement
True or false: Humoral immunity is a part of innate immunity.
False
True or false: Humoral immunity is a part of innate immunity. True false question.
False
True or false: The binding of an antibody to its specific antigen usually directly destroys that antigen.
False
True or false: The great diversity in the types of antibodies an individual can produce is largely due to each B cell of that individual being able to express antibodies that can bind to a variety of antigenic epitopes.
False
True or false: The innate and adaptive immune systems are two independently operated systems that have evolved to protect humans.
False. Reason: Discussing the innate and adaptive responses separately is helpful in understanding their function, but in reality, they represent parts of a fully integrated host defense system.
If an antibody molecule is thought of as a "Y," the stalk or bottom of the Y is the ______ fragment; the top two branches if the Y is the ______ fragments.
Fc; Fab
Which immunoglobulin type seems to have no function as a secreted antibody in the bloodstream, but is an important part of the BCR complex on the surface of B cells?
IgD
Which type of human immunoglobulin is at very low levels in serum because it becomes tightly bound by Fc receptor on basophils and mast cells shortly after it is produced?
IgE
During a primary antibody response, the first class of antibody produced is _____.
IgM
Which form of IgM is expressed on B-cell surfaces as the antibody component of the BCR?
IgM monomers
Which form of IgM is found in the bloodstream where it agglutinates bacteria, activates complement and enhances phagocytosis?
IgM pentamers
Select the best description of the B cell receptor (BCR) complex.
Membrane-bound IgM and IgD with accessory Ig alpha/beta molecules.
After recognizing non-self, the adaptive immune system responds by activating and amplifying ______.
T and B lymphocytes
Compared to a primary antibody response, the antibodies produced during a secondary antibody response have ______.
a higher affinity for the antigen
The antibody titer is ______
a measurement of serum antibody concentration
The best definition of an antigen is ______.
a self/nonself substance that elicits an immune response
The BCRs of an individual B cell are specific for ______ .
a single, unique antigen and one particular epitope on that antigen
CD8+ cytotoxic T cells receive the first of their two required signals to achieve activation through binding of their TCR complex to ______.
a specific peptide fragment presented by a class I MHC molecule on an antigen-presenting cell
CD4+ helper T cells receive the first of their two required signals to achieve activation through binding of their TCR complex to ______.
a specific peptide fragment presented by a class II MHC molecule on an antigen-presenting cell
Select three correct descriptions of human IgM.
activates complement by the classical pathway usually secreted as a polymer of 5 monomeric antibody units can agglutinate bacteria in the bloodstream
Diversity, specificity, and memory are three key characteristics of _____ immunity.
adaptive
During antigen processing, class I MHC molecules bind to peptides that originated from the ______.
all nucleated cells
As shown in the image, the VH+L portions of a B cell receptor complex function to ______, while the Igα/β portions function to ______.
bind to specific antigen; initiate signal transduction
The most important source of signal 2 for activation of naive T cells is ______.
binding of B7 on antigen-presenting cells to CD28 on T cells
Select the best definition of neutralization by antibodies.
binding of antibodies to biologically active materials, causing their inactivation
Which one of the following is an example of naturally acquired passive immunity?
breastfeeding
Some antigen molecules have several antigenic determinant sites, also called _____ , which bind to specific antibodies or T-cell receptors.
epitopes
The mammalian immune system is informed of the presence of nonself (e.g., infections) by the presence of foreign peptides that are bound and presented by ______.
class I and class II MHC molecules
During the primary antibody response, IgM appears first. The process by which antibody belonging to a different class is produced is called antibody ______.
class switching
One way that B cells generate antibody diversity is by reassortment of different gene segments to code for the variable regions of heavy and light chains, in a process called ______.
combinatorial joining
During the process of antibody gene rearrangement in B cells, what is the specific function of the RAG-1 and RAG-2 enzymes?
combinatorial joining of gene segments
The light (L) and heavy (H) polypeptide chains of all antibody molecules contain what two regions?
constant region variable region
Splicing of _____ region (C) transcripts to variable (V) region transcripts occurs only after transcription through both regions has occurred, producing a preliminary _____ molecule.
constant; mRNA
The major function of the multiple polypeptides that make up the CD3 portion of the T-cell receptor is to ______.
convert antigen binding into an intracellular signal
Activated CTLs kill target cells using either a(n) _____ pathway (utilizing perforins/granulysins) or a(n) _____ pathway (programmed cell death).
cytolytic, apoptotic
The parts of a TCR complex that generate intracellular signals are the ______.
cytoplasmic portions of some of the the CD3 polypeptides
Which type of cell expresses CD8 on its surface?
cytotoxic T cell
Splice-site variability can lead to greater diversity in antibody molecules because ______.
it has the potential to change the reading frame of the eventual RNA transcript
Select all of these cells that express class II MHC molecules, and are therefore considered to be "antigen-presenting cells" (APCs).
dendritic cells macrophages B cells
Most B cell responses to antigens require the collaboration of T-helper cells. Therefore, such responses can be called T-_____ antigen activation.
dependent
The major histocompatibility complex (MHC) is a collection of genes that encode proteins involved in ______.
distinguishing self from nonself
A single antigen molecule may have several ______.
eiptopes
The process by which intracellular antigen proteins are digested by proteasomes, transported into the ER, and loaded onto class I MHC molecules is called _____ antigen processing.
endogenous
Which type of antigen processing allows presentation of peptide fragments to CD8+ cytotoxic T cells?
endogenous
Exogenous antigen processing occurs when ______ antigens are broken down into smaller pieces and loaded into the cleft of class ______ MHC molecules for presentation.
extracellular; II (two)
Somatic mutation and variable gene splicing are two mechanisms employed by the immune system to ______.
generate antibody diversity
Which one of the following is an example of naturally acquired active immunity?
getting a cold and recovering from it
Select all correct descriptions of human IgD.
has a monomeric structure found in trace amounts in blood part of BCR complex on surface of B cells signals B cells to start antibody production upon initial antigen binding
Identify three characteristics of the adaptive immune system that are NOT a part of innate resistance.
high degree of specificity against a specific pathogens or foreign substances; generation of an enormous number of receptors for foreign substances; memory of former responses upon reexposure
When a highly polymeric antigen is capable of stimulating a B cell into antibody production without the cooperation of T-cells, it is referred to as a T-_____ antigen.
independent
The transfer or a mother's antibodies into her child, either by crossing the placenta before birth or in breast milk after birth, is an example of which type of adaptive immunity?
naturally acquired passive immunity
Select all characteristics of an antibody response to T-independent antigens.
no immunological memory low affinity for antigen membrane-bound BCRs are cross-linked
Foreign peptides derived from which three types of antigens would most likely be processed and presented on class I MHC molecules?
peptides from viruses peptides from intracellular bacteria abnormal proteins in cancerous cells
Select the two pairs of molecules utilized by activated CTLs to destroy infected/abnormal target host cells.
perforins & granulysins Fas (CD95) & Fas ligand (FasL)
B cells that have differentiated into cells specialized for antibody production are called _____ cells.
plasma
Because of the highly ______ nature of T-independent antigens (possessing numerous identical epitopes), they can activate B cells to produce antibodies by cross-linking enough ______ to stimulate the cells.
polymeric; BCRs
If a patient's antibody response to an antigen is measured and is determined to be entirely of the IgM class, the patient is most likely producing a(n) ______ response to the antigen.
primary
During antigen _____, MHC molecules are loaded with peptides, including those derived from nonself proteins.
processing
Compared to a primary antibody response, a secondary antibody response ______. (Select all that apply)
produces more total antibody has a more rapid log phase has a shorter lag phase (latent period)
Which one of the following is an example of artificially acquired active immunity?
receiving a hepatitis B vaccine
Which one of the following is an example of artificially acquired passive immunity?
receiving an injection of snake venom antitoxin antibodies produced in a horse
T cells respond to antigen fragments presented by MHC molecules through specific T-cell _____ (TCR) complexes on their plasma membrane surface.
receptor
Although there are other differences, the main difference in antigen processing of extracellular antigens versus intracellular antigens is the ______.
role of the phagolysosome instead of the proteasome to break down the antigen
Which immunoglobulin type is found as a dimer form in mucous secretions, linked together by a joining chain protein and a secretory component?
sIgA
When a naive cell receives both signal 1 and signal 2, it then ______.
secretes IL-2 to proliferate and differentiate to respond to the activating antigen
Select all correct descriptions of human IgA.
secretory form (sIgA) is the major antibody in mucosal secretions participates in immune exclusion of bacteria in the intestine
Clonal selection in B cells can be defined as ______.
selection of a single specific B cell by specific antigen, followed by expansion into numerous clone cells with the same specificity
During a B cell response to an antigen, random mutations occur in the variable region of an antibody molecule's DNA, increasing affinity for antigen. This process is called _____ hypermutation.
somatic
The phenomenon that occurs as the ends of antibody gene segments are cut and recombined in different ways (possibly with either addition or deletion of nucleotides between the joins), leading to greater possible diversity, is known as ______.
splice-site variability
Select three correct descriptions of human IgG.
the only class that can cross the placenta opsonizes bacteria and viruses neutralizes toxins and viruses
The major "histocompatibility" complex is named for the Greek word for _____ (histo) and the ability to get along (compatibility).
tissue
The serum antibody concentration is called the antibody _____.
titer
The _____ regions of the heavy and light antibody chains exhibit very different amino acid sequences, even among antibodies of the same class.
variable
Select the four mechanisms by which B cells generate antibodies that can bind to a huge diversity of epitopes.
variable splicing of antibody genes rearrangement of antibody gene segments via combinatorial joining insertion of nucleotides during combinatorial joining mutations in the genes encoding antibodies