There are two critically important aspects of adaptive immunity. The first is specificity, while the second is memory.
Missing Word
memory
Specificity and memory are the hallmarks of adaptive immunity, allowing for targeted and long-lasting protection against specific pathogens. Specificity refers to the ability of the immune system to recognize and respond to unique antigens, while memory allows for a faster and stronger response upon subsequent encounters with the same antigen.
Question 2
Humoral immunity involves the production of antibody molecules that bind to specific antigens.
Missing Word
Humoral
Humoral immunity is mediated by antibodies produced by B cells, which circulate in bodily fluids (humors) to neutralize pathogens. This contrasts with cell-mediated immunity, which involves direct action by immune cells.
Question 3
The heavy chains of an antibody molecule contain constant region segments, which help to determine its class or isotype.
Missing Word
constant
The constant region of the antibody heavy chain determines the antibody's class (IgG, IgM, IgA, IgE, IgD) and mediates effector functions like complement activation and binding to Fc receptors on immune cells. The constant region is conserved within each class.
Question 4
The variable regions of the heavy and light chains form the antigen-binding sites of an antibody.
Missing Word
antigen-binding
The variable regions, specifically the hypervariable regions or complementarity-determining regions (CDRs), of both heavy and light chains create the unique antigen-binding site. This allows for the vast diversity of antibodies needed to recognize a wide range of antigens.
Question 5
MHC molecules are used for antigen presentation to T cells.
Missing Word
presentation
MHC (Major Histocompatibility Complex) molecules are crucial for presenting processed antigens to T cells, initiating an adaptive immune response. MHC I presents antigens to cytotoxic T cells, while MHC II presents antigens to helper T cells.
Question 6
MHC II molecules are made up of two subunits (α and β) of approximately equal size, whereas MHC I molecules consist of a larger α subunit and a smaller subunit called β2 microglobulin.
Missing Word
β2 microglobulin
MHC I molecules are heterodimers consisting of a larger alpha chain and a smaller beta-2 microglobulin, while MHC II molecules consist of two subunits, alpha and beta, of roughly equal size. This structural difference is important for their distinct roles in antigen presentation.
Question 7
A cytotoxic T cell will become activated by presentation of foreign antigen associated with an MHC I molecule.
Missing Word
cytotoxic
Cytotoxic T cells (CTLs) recognize antigens presented on MHC I molecules, which are found on all nucleated cells. This allows CTLs to identify and kill infected or cancerous cells.
Question 8
A helper T cell will become activated by presentation of foreign antigen in association with an MHC II molecule.
Missing Word
helper
Helper T cells recognize antigens presented on MHC II molecules, which are primarily found on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells. Activation of helper T cells is crucial for coordinating the adaptive immune response.
Question 9
A TCR is a protein dimer embedded in the plasma membrane of a T cell. The variable region of each of the two protein chains is what gives it the capability to bind to a presented antigen.
Missing Word
variable
The T cell receptor (TCR) binds to peptide antigens presented by MHC molecules. The variable regions of the TCR chains determine the specificity of the TCR for a particular antigen-MHC complex.
Question 10
Peripheral tolerance mechanisms function on T cells after they mature and exit the thymus.
Missing Word
thymus
Peripheral tolerance mechanisms prevent autoimmunity by eliminating or inactivating self-reactive T cells that escaped negative selection in the thymus. These mechanisms include anergy, suppression by regulatory T cells, and activation-induced cell death.
Question 11
Both memory and effector T cells are produced during differentiation of activated T cells.
Missing Word
memory
When T cells are activated by antigen, they differentiate into effector cells that mediate immediate immune responses and memory cells that provide long-lasting immunity. Memory T cells are crucial for a faster and more robust response upon re-encounter with the same antigen.
Question 12
T-dependent antigens can stimulate B cells to become activated but require cytokine assistance delivered by helper T cells.
Missing Word
T-dependent
T-dependent antigens require the help of T helper cells to activate B cells, leading to antibody production and immunological memory. This collaboration is crucial for robust responses against protein antigens, as T cells provide necessary co-stimulatory signals and cytokines.
Question 13
T-independent antigens can stimulate B cells to become activated and secrete antibodies without assistance from helper T cells. These antigens possess repetitive antigenic epitopes that cross-link BCRs.
Missing Word
repetitive
T-independent antigens, like polysaccharides, directly stimulate B cells due to their repetitive epitopes that cross-link B cell receptors (BCRs). This cross-linking provides a strong activation signal, bypassing the need for T cell help, but typically results in weaker and shorter-lived antibody responses.
Question 14
A(n) attenuated pathogen is in a weakened state; it is still capable of stimulating an immune response but does not cause a disease.
Missing Word
attenuated
An attenuated pathogen is weakened, losing its ability to cause disease while retaining its immunogenicity. This makes it suitable for vaccines, as it can stimulate an immune response without causing severe illness, leading to protective immunity.
Question 15
Artificial passive immunity occurs when antibodies from one individual are harvested and given to another to protect against disease or treat active disease.
Missing Words
Artificial, passive
Artificial passive immunity involves the transfer of pre-formed antibodies from one individual to another, providing immediate but temporary protection. This is 'artificial' because the recipient did not actively produce the antibodies themselves, and 'passive' because the protection is conferred by transferred antibodies.
Question 16
In the practice of variolation, scabs from smallpox victims were used to immunize susceptible individuals against smallpox.
Missing Word
variolation
Variolation was an early method of immunization against smallpox, involving inoculation with material from smallpox lesions. This practice induced a milder form of the disease, leading to immunity against subsequent, more severe infections, paving the way for modern vaccination.