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25 Jun 2019

IMMUNITY: Hello, I am trying to understand how our T and B cells have receptors for each specific antigen. How can there be a specific receptor for each antigen when there are so much different antigens? In a situation where a population is exposed to a new bacteria, how will their cells develop receptors specific for that new bacteria assuming that some of the population develops immunity and lives?

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Collen VonLv2

25 Jun 2019

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True / False Questions

01. _____ Antibody is composed of 2identical long heavy chains and 2 identical shorter lightchains.

02. _____ Variable (V) and constant(C) regions are part of both heavy and light chains.

03. _____ Variable regions for heavyand light chains from the same antibody molecule are alwaysidentical.

04. _____ Variable region of lightchains are encoded by the DNA sequences that contain rearranged V,D, and J segments.

05. _____ Fc part of the antibody isnot important, F(abâ)₂ fragment has the same binding andeffector capacity.

06. _____ Fab fragments are generatedby alternative splicing.

07. _____ J chain is used as asurrogate light chain during pre-B cell receptor testing forsuccessful V(D)J rearrangement.

08. _____ Binding of the antigen byantibody is stabilized by disulfide bonds.

09. _____ RAG1/2 are always expressedin B cells at high level, because B cells need RAG1/2 to constantlyrearrange their V regions.

10. _____ âNâ (non template)nucleotides are added by TdT.

11. _____ The 12/23 rule is appliedduring class switching.

12. _____ For B cells, V(D)Jrecombination occurs only in the bone marrow.

13. _____ The process of somatichypermutation helps to improve specificity of the antibody.

14. _____ In late pro-B cells, Vsegment is rearranged with DJ segments.

15. _____ Failure to eliminateself-reactive B cells may lead to serious autoimmune diseases.

16. _____ Mature, naÃ¯ve B cellsexpress IgD and any of the other classes of antibody (IgM, IgG,IgA, or IgE) on their surfaces.

17. _____ B1 cells are present in theperitoneal cavity, pleural spaces and brain.

18. _____ AID (activation inducedcytidine deaminase) is expressed only in B cells and it canintroduce breaks in double stranded DNA.

19. _____ Different classes (isotypes)of antibodies have different effector functions, which aretriggered by special receptors expressed by a variety of cells.

20. _____ Plasma cells are terminallydifferentiated cells that produce large quantities ofantibodies.

21. _____ Repeated exposure to thesame antigen eventually leads to immunological exhaustion and lackof immunity, because there is no room for new plasma cells in thebone marrow.

22. _____ Germinal centers arespecialized sites within the bone marrow where Ig genes ofactivated B cells undergo affinity maturation.

23. _____ B cells can present antigensto T helper cells.

24. _____ Co-stimulatory molecules arerequired for efficient generation of memory B cells.

25. _____ Lymphocytes migrate to thelymphoid tissues in response to chemokines.

26. _____ Class switching duringgerminal center reaction is a random process.

27. _____ T cell independent responsescan generate strong and long lasting B cell memory.

28. _____ Fc receptors that arepresent on many different cell types are crucial for removal of thepathogens.

29. _____ The ideal vaccine should bedesigned to mimic the natural course of infection without causingsymptoms of the disease.

30. _____ The protective immunity canbe generated against any pathogen because there is virtuallyunlimited number of possible V regions, thus any antigen can berecognize by an antibody.

oliverhinoceros960

Functional Magnetic Resonance Imaging is a tool that has been very useful in identifying what parts of the brain do what. Scientists can have a person perform some particular activity and then look for active areas in the brain. How does fMRI work?

	A.	It takes a picture of the inside of the brain according to electricity levels. The more electrical current in the area, the more active it is.
	B.	It takes a picture of the inside of the brain according to blood flow. More blood flow indicates more activity in that area.
	C.	It takes images of thin layers of the brain and the more electrical activity in a layer, the more magnetic it is and this shows up in fMRI.
	D.	Electrodes attached to the skull can trigger activity in particular brain areas which then trigger a person to perform certain behaviors.
	E.	It takes a picture of the brain according to oxygen levels. More oxygen in an area indicates more activity in that area.

The strategy of vaccination to fight diseases uses what type of immunity?

	A.	Non-specific immunity
	B.	Cell-mediated immunity
	C.	Natural immunity
	D.	Specific immunity
	E.	Passive immunity

If you came into contact with Vibrio, what defense do you have to keep it from even getting to your intestines?

	A.	Your skin is an effective barrier against bacteria you come in contact with.
	B.	Antimicrobial enzymes in saliva
	C.	Acid in the stomach
	D.	Mucous membranes in the digestive and respiratory tract
	E.	All of the above

What do B cells do when they identify a pathogen?

	A.	Engulf and eat it
	B.	Kill it
	C.	Produce antigens to bind to the pathogen and memory cells to guard against future infection.
	D.	Produce antibodies to bind to the pathogen and memory cells to guard against future infection.
	E.	Engage helper T cells to fight the infection

There are chemical signals that call on non-infected cells to help fight a virus. Which are they?

	A.	Complement proteins
	B.	Macrophages
	C.	B cells
	D.	Interferons
	E.	Natural killer cells

When someone gets a bone marrow transplant, they have to be quarantined and carefully protected from pathogens for a period of time afterward. Why?

	A.	Bone marrow produces the main cells involved in the specific immune response, so these patients are at special risk of infection until they build up enough marrow to produce sufficient cells.
	B.	Bone marrow produces blood cells, so they have insufficient circulation for a period of time so their immune system lacks the energy to fight off any infection.
	C.	Anytime a foreign substance, even someone else's bone marrow, is introduced to a body, there is an extra risk of infection.
	D.	A common complication of bone marrow transplants is infection, and doctor's don't want the infection to spread to others.
	E.	It's a traumatic procedure, and any extra stress on their body could kill them.

1. Why is the process of gene rearrangement used in creating antibodies and T-cell receptors (TCRs) so important?

A. This is how our systems produce memory of pervious exposures, a key trait in adaptive immune responses.

B. Without it, we would need a single gene for every antibody and TCR required to mount all the possible responses need ed during our lives

C. interactions with antigens stimulate cells to initiate these processes, building the best and strongest response possible to the antigen

D. this is the same DNA altering process that leads to cancer. Understanding it leads to better treatments for cancer

2. Which of the following is NOT an antimicrobial substance?

A. keratin

B. Lysozyme

C. Defensins

D. Lactoferrins

E. Peroxidases

3. Which of the following is NOT an outcome of fever?

A. Direct destruction of microbes

B. increased release of pro-inflammatory cytokines

C. increased production of lymphocytes

D. increased phagocytic killing by leukocytes

E. increased production of interferons

4. Which of the following pattern recognition receptors is/are anchored in the host cell membrane?

A. Only C-type lectin receptors (CLRs)

B. Only RIG-like receptors (RLRs)

C. TLR and CLRs

D. Only toll-like receptors (TLRs)

E. NLRs and RLRs

F. Only NOD-like receptors (NLRs)

5. Fever allows the body to fight microbial invaders by which of the following mechanisms?

A.Fever plays all of these roles in the body

B. Fever prevents microbes with lower optimum temperatures from growing, giving the immune system time to eliminate those cells

C. Fever increases the inflammatory response, but reduces the production of interferons unless the invader is a dsRNA virus

D. A moderate fever reduces the inflammatory response but stimulates phagocytic activity in neutrophils and eosinophils

E. Fever increases the multiplication of lymphocytes and enhances the release of substances that attract basophils that then engulf the microbial invader

6. According to the clonal selection theory

A. Each B cell is already programmed to produce a specific antibody

B. B cells producing autoantibodies are eliminated in the thymus

C. Self-reactive T cells are killed in the thymus AND B cells producingautoantibodies are eliminated in the thymus

D. Seld-reactive T cells are killed in the thymus

7. Apoptosis

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

B. refers to the transformation of B cells into plasma cells

C. is induced in target cells by effector T cytotoxic cell AND results specifically in T cell death

D. results specifically in T cell death AND refers to the transformation of B cells into plama cells

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