Question 1

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

Accepted Answer

Gene rearrangement is a well-known process that occurs during the development of the immune system. It plays a crucial role in the generation of the diverse repertoire of antibody molecules that can specifically recognize and bind to a wide range of foreign antigens. This process involves the random rearrangement and joining of different gene segments encoding the variable regions of antibody heavy and light chains, leading to the creation of unique antibody specificities.

Question 2

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

Accepted Answer

Both the central portion of a T-cell receptor complex and the center of the B-cell receptor complex bind epitopes (small amino acid sections of antigen molecules).

Question 3

T cell independent antigens lead to a memory response.

Accepted Answer

T cell independent antigens do not lead to a memory response, as they do not involve T cell activation and stimulation of B cell memory development. Instead, they often lead to short-lived antibody responses.

Question 4

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

Accepted Answer

T-cell receptors require the antigen to be presented to them by an MHC molecule, while B-cell receptors can bind directly to free-floating antigen. Additionally, T-cell receptors have a different structure with four protein chains, while B-cell receptors have two protein chains.

Question 5

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

Accepted Answer

Tonsils are secondary lymphoid organs that help to provide a constant response to microbes in the oral cavity, preventing them from spreading to other areas. Removing the tonsils hinders the body's ability to fight these infections, making the person more susceptible.

Question 6

The best possible analogy available below for the way in which variable (V), diversity (D), and joining (J) antibody gene segments get put together to create the diversity possible in hypervariable regions is

Accepted Answer

The analogy of a bingo game is the best choice for explaining the way in which variable (V), diversity (D), and joining (J) antibody gene segments get put together to create the diversity possible in hypervariable regions. The random selection process is similar to the way in which the V, D, and J segments are combined to form a functional molecule, and the variations in the combinations depend on the antigen that will eventually bind to the molecule.

Question 7

T cells are responsible for directly manufacturing antibodies.

Accepted Answer

T cells do not manufacture antibodies directly. They stimulate B cells to differentiate into plasma cells, which then produce and secrete antibodies.

Question 8

Why would a person who has AIDS be more susceptible to the bacterium that causes tuberculosis?

Accepted Answer

HIV destroys CD4+ helper T-cells, which are necessary for activating macrophages that destroy the bacterium that causes tuberculosis. Without the CD4+ T-cells, there won't be effective clearance of the bacterium.

Question 9

A terrorist mad scientist develops a new blood-borne virus that will completely shut down presentation of viral epitopes on MHC molecules in the cells it infects. He produces an internet video describing it and how it will be indestructible by CD8⁺ cytotoxic T-cells and will kill millions (if not billions) of people. The medical community quickly denounces and discredits his plan as impossible, and the whole thing is quickly forgotten-why?

Accepted Answer

The answer of A terrorist mad scientist develops a new...

Question 10

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

Accepted Answer

If the IgG bound to the phagocyte before opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen. This is because the phagocyte recognizes and ingests foreign particles by their surface proteins, and if the IgG is already bound to the phagocyte, it would be recognized as a foreign particle and ingested before it has a chance to bind to the pathogen. By reacting with the antigen before being recognized by the phagocyte, the IgG can bind to the pathogen and allow the phagocyte to recognize and engulf the pathogen opsonized with IgG.

Question 11

IgA is the most abundant immunoglobulin made by the body.

Accepted Answer

IgA is the most abundant immunoglobulin made by the body, accounting for about 75% of all immunoglobulins produced.

Question 12

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

Accepted Answer

Some epitopes are dependent on 3D conformation (conformational epitopes), while some simply depend on the primary order of amino acids (linear epitopes). So, denaturation may destroy some epitopes while leaving others intact.

Question 13

T cell receptors are identical to antibodies.

Accepted Answer

T cell receptors (TCRs) are different from antibodies. Antibodies are produced by B cells and can recognize and bind to a variety of targets, including pathogens and foreign substances. TCRs are found on the surface of T cells and only recognize fragments of antigens that are displayed by other cells, such as infected or cancerous cells. While both TCRs and antibodies play important roles in the immune system, they are structurally and functionally distinct.

Question 14

A physician is seeking ways to increase the fine-tuning of antibody immune responses that occurs naturally during affinity maturation. The goal is to create 'super antibodies' with intensely high affinity for antigens. She decides to use a drug that can be injected into lymph nodes that will be highly mutagenic specifically to B-cells that are undergoing activation. Is this a good idea? Why or why not?

Accepted Answer

The process of affinity maturation is not solely dependent on the number of mutations that occur, but rather the selection of B cells with higher affinity for the antigen. Increasing the number of mutations may not necessarily increase the affinity of the antibodies. Additionally, the injection of a mutagenic drug can have harmful effects on the body, including the risk of cancer. Therefore, it is not a good idea to use a drug that is highly mutagenic to boost affinity maturation.

Quiz 15: The Adaptive Immune Response