Ch. 27 Micro Hw
The ________ is a highly conserved amino acid sequence found in immunoglobulin, TCR, and MHC proteins.
C domain
Which event happens first during cytotoxic T-cell activation?
CD8 binds to MHC molecules of infected cells
Which of the following are found on the surfaces of all nucleated cells?
Class I MHC proteins
Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
What would a virally infected skin epithelial cell have on its cell surface?
Class I MHC with skin cell antigens
A person who has AIDS contracts rare and often life-threatening infections because their helper T cell count is so low. Which of the following components of the immune response still respond to antigen despite the low helper T cell count?
Clonal selection of B cells
Which type of cell directly attacks infected cells?
Cytotoxic T-cells
HIV directly infects T-cells. Why is this problematic for cell-mediated immunity?
Cytotoxic T-cells begin to attack the virally infected T-cells, reducing the number of T-cells in the body.
Which of the following are likely to be found on an MHC-I protein?
Damaged mitochondrial fragment
According to the animation, on what day does IgM first appear?
Day five
According to the animation, on which day does the production of IgG occur in the secondary response?
Day five
memory cells
Differentiated B cells that are stored in lymph nodes to provide protection against future infections by the same pathogen
When does MHC-II loading occur?
During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens
What makes agglutination by antibodies possible?
Each antibody has at least two antigen-binding sites.
How can a sufficient humoral immune response occur if a plasma cell only lives for a few days?
Each plasma cell can produce up to 2000 antibodies every second.
Somatic hypermutation mechanisms generate TCR diversity.
False
Th cells interact directly with pathogens.
False
Tolerance is the acquired ability to make an adaptive immune response directed to self-antigens.
False
Which molecule triggers apoptosis?
Granzyme
What is the role of helper T cells in the adaptive immune response?
Helper T cells activate B cells and cytotoxic T lymphocytes to kill infected host cells.
Cytokines are produced by which of the following cells?
Helper T-cells
How do helper T-cells and cytotoxic T-cells work together?
Helper T-cells produce cytokines to activate other cells of the immune system.
Which part of the adaptive immune response involves B cells?
Humoral
humoral immunity
Immunological response brought about by antibody production
innate immunity
Includes cilia, mucous membranes, dendritic cells
Cytotoxic T cells
Kills infected host cells
Th cells
Lymphocytes that activate B cells and CTLs
Based on the animation, T cells recognized the antigen displayed by what protein of the B cell?
MHC
Which proteins on the antigen-presenting cell are recognized by the helper T-cell?
MHC proteins
What is the most important cause of tissue rejection?
MHC proteins are different in different individuals and cause the immune system to recognize cells as not being self.
Which of the cells listed below can present antigens on Class II MHC proteins?
Macrophages
The student who caught the cold caused by this specific Rhinovirus was exposed to the exact same Rhinovirus 18 months later. What component of the immune system will protect her from getting the same cold again?
Memory B cells
Which cells are involved in a secondary response?
Memory B cells and plasma cells
Why would a body cell that is not a phagocyte need to present antigens?
Non-phagocytic body cells can become infected with a virus.
Where are MHC molecules located on a cell?
On the surface of the cell
Paul had chicken pox when he was 5 years old. Nicholas received the chicken pox vaccines. Which type of immunity does each man have?
Paul has natural active immunity while Nicholas has artificial active immunity.
Dendritic cells
Phagocytes that engulf anything foreign. Eventually display epitope to helper T cells using MHC 1 or 2
Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
Phagolysosome
What is produced by the process of clonal expansion?
Plasma cells and memory B cells
What is the role of plasma cells in humoral immunity?
Plasma cells produce antibodies.
Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells?
Recognition of infected host cell using its CD4 glycoprotein
Which of the following is an example of artificially acquired passive immunity?
Someone suspected of exposure to Clostridium tetani is given an injection of antibodies (antiserum).
T cells recognize antigens with their
T cell receptors
In B cell selection and tolerance, if no signal is generated from ________ cells, the B cells remain unresponsive.
T helper cells
Antigen-presenting cells present antigens to
T lymphocytes
An antigen that is potent enough to activate a B cell on its own is known as
T-independent antigens.
Which receptor on the helper T-cell recognizes the specific antigen from an antigen-presenting cell?
TCR
According to the animation, for approximately how many days is IgG present in the serum?
Ten days
Natural killer cells are activated by
Th1 cells
How might a pathogenic bacterium be affected by antibodies?
The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria
Which organelle assists directly with the presentation of MHC-I antigens?
The endoplasmic reticulum
Which of the following best characterizes clonal selection?
The production of identical B cells producing the same antibody
How is the secondary response different from the primary response in terms of antibody concentration in the blood?
The secondary response is faster and produces more antibodies than the primary response.
How are B cell receptors able to bind to so many different antigens?
The variable region binds to antigens through noncovalent interactions. Because of the variation in the variable regions, the receptors are able to bind to a wide variety of antigens.
What is a feature of the small fragments presented by MHC-I proteins?
They are small peptides, roughly 8-10 amino acids long
How do phagocytes communicate to other cells what they have captured?
They present antigens from engulfed foreign cells.
What is the fate of activated cytotoxic T-cells?
They proliferate into a clone of cells specific to the same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.
Which of the following is an example of humoral immunity?
the production of antibodies by B cells
________ is the acquired inability to mount an adaptive immune response against self.
Tolerance
Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
Tom would not be able to destroy virally-infected cells.
Affinity maturation is one of the factors responsible for a stronger secondary immune response.
True
Each antigen-reactive B cell or T cell has a cell surface receptor for a single antigen epitope.
True
In clonal expansion, B cells that have not interacted with an antigen do not proliferate.
True
Self-reactive T cells are eliminated during the development of tolerance in the immune system.
True
TCRs recognize epitopes only after the immunogens have been partially degraded.
True
The use of antivenom to treat a snakebite is an example of artificial passive immunity.
True
Immature B cell
Uses BCR to recognize epitope. First step in clonal selection
The primary immune response involves
a slow rise in the concentration of antibodies, followed by a gradual decline.
An anamnestic response is
another name for secondary response.
A serum containing antigen-specific antibodies is called an
antiserum.
The two-stage thymic selection process for selecting self-tolerant, antigen-reactive T cells results in
clonal deletion
The part of the antigen recognized by the antibody or TCR is called the
epitope
Antibody-mediated immunity is particularly effective against
extracellular pathogens.
The major histocompatibility complex in humans is also called the
human leukocyte antigen (HLA).
Antibodies are a part of which type of immunity?
humoral
Which of the following contribute to the limitless diversity generated from a relatively fixed number of immunoglobulin genes?
hypermutation, random heavy and light chain reassortment, and somatic recombination
cellular immunity
immunological response that kills infected host cells
Antigen processing and presentation
is a way for a cell to give information about its activities.
Which of the following presents processed antigens to T cells?
major histocompatibility complex proteins
Place the following steps of phagocytosis in the order that they occur: 1. Endosome fuses with lysozome 2. Dendritic cell engulfs Rhinovirus 3. Epitopes are attached to MHC-II 4. Digestion of the Rhinovirus 5. MHC-II plus the attached epitope move to the outside of the dendritic cell
2,1,4,3,5
Correctly order the steps involved cellular immunity: 1. The Tc recognizes the infected host cell 2. The Tc interacts with epitope presented by MHC-I on the dendritic cell 3. The Tc secretes perforin and granzyme, causing apoptosis 4. The helper T cell activates the Tc cell
2,4,1,3
Which of the following is a probable lifespan of memory B cells?
5 years
Which is an example of acquisition of natural passive immunity?
A fetus protected from disease by its mother's antibodies
Antibodies are found in
milk, mucosal secretions, and serum.
The transfer of antibodies through the placenta from mother to fetus is an example of
natural passive immunity.
Which of the following is NOT a step that ultimately leads to antibody production?
Activation of cytotoxic T cells by helper T cells
Which of the following statements is true?
Adaptive defenses include both humoral and cellular immunity.
When do helper T-cells develop into TH1 or TH2 cells?
After proliferation into a clonal population
What is meant by the clonal expansion of a B cell?
An activated B cell divides into cells that give rise to memory B cells and plasma cells.
Natural killer cells like Tc cells use ________ and granzymes to kill their targets without prior exposure or contact with the foreign cells.
perforin
Some activated B cells differentiate into ________ cells that secrete antibodies, and others into ________ cells.
plasma / memory B
What is apoptosis?
programmed cell death
Proteins derived from infecting viruses are taken up and digested in the cytoplasm in a structure called the
proteasome
TH2 cells produce cytokines that activate
B cells
Which pair of molecules do NOT directly interact with one another?
BCR and TCR
What is the function of the CD8 receptor?
Bind to MHC molecules
