Nokea
Choose the correct sequence in an allergic reaction.
- A. Allergen → mast cells → histamine → B cells → IgE antibodies
- B. Allergen → IgE antibodies → B cells → histamine → mast cells
- C. Allergen → B cells → IgE antibodies → mast cells → histamine
- D. Allergen → histamine → mast cells → IgE antibodies → B cells
Correct Answer: C
Rationale: Rationale for Answer C:
1. Allergen exposure triggers B cells to produce IgE antibodies specific to the allergen.
2. IgE antibodies bind to mast cells sensitizing them.
3. Upon re-exposure to allergen, allergen binds to IgE on mast cells.
4. This triggers release of histamine and other chemicals causing allergic symptoms.
Summary:
- Choice A: Incorrect because B cells do not produce IgE antibodies before allergen exposure.
- Choice B: Incorrect because IgE antibodies are produced by B cells, not the other way around.
- Choice D: Incorrect because histamine is released after allergen binds to IgE on sensitized mast cells.
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Class switching of immunoglobulins occurs
- A. Usually with booster immunizations, going from IgM to IgG
- B. binds complement
- C. causes the histamine release
- D. mediates immunoglobulin class switching
Correct Answer: A
Rationale: The correct answer is A because class switching of immunoglobulins typically occurs during an immune response, leading to the production of antibodies of different classes like IgM to IgG. This process helps enhance the immune response and memory. Choice B, binding complement, refers to the function of antibodies in the classical pathway of the complement system, not class switching. Choice C, causing histamine release, is typically associated with IgE antibodies in allergic reactions, not class switching. Choice D, mediating immunoglobulin class switching, is too vague and does not provide a clear explanation compared to choice A.
Which of the following statements is incorrect?
- A. Activation of receptors such as TLRs often precedes inflammasome formation
- B. Extracellular ATP triggers inflammasome formation
- C. Some environmental triggers, such as asbestos, can induce inflammasome formation
- D. NLRP3 is found in complex with pro-caspase 1 in resting, non-activated cells
Correct Answer: D
Rationale: The correct answer is D because NLRP3 is not found in complex with pro-caspase 1 in resting, non-activated cells. Inflammasome formation requires assembly of NLRP3 with ASC and pro-caspase 1. Choices A, B, and C are correct statements because activation of receptors like TLRs can trigger inflammasome formation, extracellular ATP can induce inflammasome formation, and environmental triggers such as asbestos can also lead to inflammasome activation.
A good vaccine will:
- A. Be highly pathogenic
- B. Be highly immunogenic
- C. Induce herd immunity in a vaccinated individual
- D. All of the above
Correct Answer: B
Rationale: The correct answer is B: Be highly immunogenic. A good vaccine should effectively stimulate the immune system to produce a strong immune response against the targeted pathogen while being safe for the individual. This is crucial for developing immunity without causing harm.
Choice A (Be highly pathogenic) is incorrect because a vaccine should not cause disease or harm to the individual receiving it. Choice C (Induce herd immunity in a vaccinated individual) is also incorrect as herd immunity refers to protection of a population, not an individual.
In summary, a good vaccine should be highly immunogenic to effectively trigger an immune response without causing harm, leading to protection against the targeted pathogen.
What is the main purpose of complement component C5a?
- A. Opsonization
- B. Cell lysis
- C. Recruitment and activation of immune cells
- D. Inhibition of inflammation
Correct Answer: C
Rationale: The correct answer is C: Recruitment and activation of immune cells. C5a is a potent chemoattractant that attracts immune cells to the site of infection or inflammation. It also activates these immune cells, leading to enhanced immune responses. Option A (Opsonization) and B (Cell lysis) are not the main functions of C5a. Option D (Inhibition of inflammation) is incorrect because C5a actually promotes inflammation by recruiting and activating immune cells.
Identify the correct statement(s). In prokaryotes:
- A. Translation begins after transcription is finished.
- B. Messenger RNA is not co-linear with the DNA template.
- C. 5s, 16s, and 28s ribosomal RNA's are present.
- D. 50s and 30s ribosomal subunits are necessary for protein synthesis.
Correct Answer: d
Rationale: The correct answer is D because in prokaryotes, 50s and 30s ribosomal subunits combine to form the 70s ribosome, which is necessary for protein synthesis. Firstly, ribosomes are composed of two subunits, and in prokaryotes, these are the 50s and 30s subunits. Secondly, these subunits come together during translation to form the functional ribosome. Therefore, these ribosomal subunits are indeed necessary for protein synthesis in prokaryotes.
A: Incorrect. Translation can begin before transcription is finished in prokaryotes due to their lack of a nuclear membrane.
B: Incorrect. Messenger RNA in prokaryotes is co-linear with the DNA template as they do not undergo RNA splicing like eukaryotes.
C: Incorrect. In prokaryotes, the ribosomal RNA present is the 16s, 23s, and 5s, not 28s.