BIOM20001 Lecture Notes - Lecture 53: Cholera Toxin, Clostridium, Immunoglobulin G

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plumdeer622

6 Oct 2018

School

University of Melbourne

Department

Biomedicine

Course

BIOM20001

Professor

All

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Document Summary

Antibodies have 2 identical heavy chains and two identical light chains. Constant region (fc) can take one of 5 forms (isotypes) Variable region (fab) can take one of an almost infinite variety of forms - specificity of antibodies. An individual can make an infinite variety of binding sites (around 1011 in humans) for an infinite array of antibodies. The antibody repertoire can bind an infinite array of antigens. Function of antibodies is to recognize and bind antigen directly in plasma and tissue fluids. Antigen binding is the function of the fab region. Antibody affinity is a measure of the strength of the bond between an antibodies binding site and an antigen. Usually the higher the affinity the better the outcome of antigen antibody binding. A single b cell makes an antibody of a single specificity but it can change its isotype (fc region) There are 5 isotypes determined by constant regions of heavy chain (fc region)

Related Questions

Question 1

The antigen specificity of a BCR...

A.	depends on the isotype of that BCR.

B.	is the same as the antigen specificity of the secreted form of antibody produced by that cell.

C.	is different for each of the BCRs on a cell.

D.	is different for each of the Fab regions of the BCR.

Question 2

All BCRs on the surface of a B cell in a lymph node...

A.	will have the same type of light chain (kappa/lambda).

B.	will have the same type of light chain with the same exact amino acid sequence.

C.	will each have a different type of light chain.

D.	will have a lambda light chain on one Fab and a kappa light chain on the other Fab.

Question 3

The isotype of an antibody is...

A.	determined by the light chain.

B.	another word for an immunoglobulin Fab region.

C.	determined by the heavy chain constant region.

D.	determined by the Fc portion.

E.	None of the above are correct

Question 4

Characteristics of lgG are...

A.	a molecular weight of 900,000 and 10 antigen binding sites in the secreted form.

B.	165,000 molecular weight in the monomeric form but it is usually secreted as dimer.

C.	the presence of more heavy chain constant regions than most antibodies but the lowest concentration in blood.

D.	150,000 molecular weight and the highest concentrations of all antibodies in blood.

E.	None of the above describe IgG.

Question 5

Characteristics of lgM are...

A.	900,000 molecular weight and the secreted form has 10 antigen binding sites.

B.	165,000 molecular weight in the monomeric form but it is usually secreted as dimer.

C	.the presence of more heavy chain constant regions than most antibodies but the lowest concentration in blood.

D.	150,000 molecular weight and the highest concentrations of all antibodies in blood.

E.	None of the above describe IgM.

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

Please briefly explain reasoning for all questions.

Which of the following is a component of a vertebrate kidney? (Select all correct choices.)

	glomerulus
	Bowman's capsule
	renal tubules
	collecting ducts
	Malphigian tubules

In organisms, the ability to control osmosis depends on the properties of the plasma membranes of individual cells. Based on their ability to permit the free movement of water and some solutes, these membranes are best described as: (select all correct choices)

	impermeable.
	permeable.
	semipermeable.
	diffusible.
	impervious.

True or false: The inner cell mass of the blastocyst becomes the embryo, while the outer cell layer of the blastocyst forms part of the placenta.

	true
	false

Which of the following accurately characterizes the early cleavage divisions in most animals, although not necessarily in mammals?

	They do not involve an increase in the size of the zygote.
	They are directed by the zygoteâs genome.
	They are relatively slow.
	They do not occur at the same time, so at any given moment the zygote may have an odd number of cells.
	All of these choices are correct.

A key difference between hormonal regulation of the reproductive systems of males and females is that:

	LH and FSH are released only in females.
	LH and FSH are released only in males.
	LH and FSH are released cyclically in females but nearly continuously in males.
	LH is released in males and FSH is released in females.
	LH is released continuously in males and FSH is released cyclically in females.

Compared to sexual reproduction, asexual reproduction: (select all correct choices)

	requires less investment in attracting mates.
	allows much more rapid population growth.
	is rarely found as the sole mechanism of reproduction.
	results in the production of genetically identical cells or individuals.
	involves meiosis and fertilization as core processes.

True or false: In response to LH and FSH, ovaries secrete estrogen and progesterone.

	true
	false

During the luteal phase of the menstrual cycle, if the oocyte is not fertilized, a number of events occur which are listed below. Select the answer that places the events in the correct chronological order.

Events:
1. the lining of the uterus is shed
2. the corpus luteum secretes progesterone
3. follicle cells are converted to the corpus luteum
4. the corpus luteum degenerates
5. estrogen and progesterone levels fall

	3, 2, 4, 5, 1
	1, 2, 3, 4, 5
	2, 4, 3, 1, 5
	4, 3, 2, 1, 5
	5, 2, 3, 4, 1

If an antibody is missing its Fc fragment, what would happen if this antibody encounters its target antigen in the bloodstream? Select all correct choices.

	The antibody would be able to bind the antigen at a specific epitope.
	The antibody would be able to bind the antigen, but not at an epitope site.
	The antibody would not be able to bind to the antigen.
	The antibody would be able to activate components of the complement system.
	The antibody would not be able to activate components of the complement system.

10)

If an individual carries a mutation that results in a complete lack of MHC class I proteins, how would the individualâs immune response be affected? Select all correct choices.

	Memory cell antibodies would not be able to attach to antigen epitopes.
	Cytotoxic T cells would not be able to target (and destroy) infected cells.
	Helper T cells would not be able to interact with antigen-presenting cells.
	Plasma cell antibodies would not be able to attach to antigen epitopes.

11)

If an individual carries a mutation that results in a complete lack of MHC class I proteins, how would the individualâs immune response be affected? Select all correct choices.

	Memory cell antibodies would not be able to attach to antigen epitopes.
	Cytotoxic T cells would not be able to target (and destroy) infected cells.
	Helper T cells would not be able to interact with antigen-presenting cells.
	Plasma cell antibodies would not be able to attach to antigen epitopes.

12)

Which of the following statements is true regarding T cell receptors? Select all correct choices.

	They recognize antigen-MHC complexes.
	They contain variable and constant regions.
	They are composed of two heavy (H) chains and two light (L) chains.
	They are formed by the rearrangement of V, J, C, and D gene segments.
	They can be found in the bloodstream independent of T cells.

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BIOM20001 Lecture Notes - Lecture 53: Cholera Toxin, Clostridium, Immunoglobulin G

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