Nokea
What is the role of complement component C3b in immune responses?
- A. Initiates MAC formation
- B. Acts as an opsonin to enhance phagocytosis
- C. Triggers inflammation
- D. Neutralizes cytokines
Correct Answer: B
Rationale: The correct answer is B: C3b acts as an opsonin to enhance phagocytosis. C3b binds to pathogens and enhances their recognition by phagocytic cells, facilitating their engulfment and destruction. This process is crucial for efficient immune responses. A, MAC formation, is initiated by the membrane attack complex, not C3b. C, inflammation, is triggered by various mediators such as histamine and cytokines, not C3b. D, neutralizing cytokines, is not a function of C3b; cytokines are regulatory proteins involved in immune responses.
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The nurse is admitting a patient to the clinical unit from surgery. Being alert to potential fluid volume alterations, what assessment data will be important for the nurse to monitor to identify early changes in the patient’s postoperative fluid volume (select all that apply)?
- A. Intake and output
- B. Skin turgor
- C. Lung sounds
- D. Respiratory rate
Correct Answer: A
Rationale: Monitoring intake/output, skin turgor, lung sounds, and respiratory rate helps detect dehydration, edema, or fluid overload early after surgery.
Which of the following statements is NOT true
- A. Light chains isotypes are functionally different
- B. The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell
- C. Both heavy and light chain domains assume a compact barrel structure
- D. The hinge region assumes a more open and flexible structure
Correct Answer: A
Rationale: The correct answer is A: Light chains isotypes are functionally different. This statement is NOT true because light chain isotypes (kappa and lambda) have distinct primary structures but serve the same function in antigen binding. The heavy chain determines the effector function of antibodies. The other choices are correct: B) The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell, as both use the same variable regions for antigen recognition. C) Both heavy and light chain domains assume a compact barrel structure, which is essential for antibody stability and function. D) The hinge region assumes a more open and flexible structure, allowing antibodies to bind antigens at different orientations.
Select incorrect mechanism for the development of autoimmune disorder.
- A. A second exposure to an allergen.
- B. Cross-reaction of antibodies formed against foreign antigens with self-antigens.
- C. Exposure of previously 'hidden' self-antigens to the adaptive immune system.
- D. Mutation followed by the appearance of membrane proteins not previously present.
Correct Answer: A
Rationale: The correct answer is A. A second exposure to an allergen does not lead to the development of autoimmune disorders. The key mechanisms involved in autoimmune disorders are self-tolerance breakdown and immune system attacking self-antigens.
Explanation:
1. B: Cross-reaction of antibodies formed against foreign antigens with self-antigens is a possible mechanism for autoimmune disorders.
2. C: Exposure of previously 'hidden' self-antigens to the adaptive immune system can trigger autoimmune responses.
3. D: Mutation followed by the appearance of membrane proteins not previously present can lead to autoimmune disorders, as the immune system may recognize these proteins as foreign.
Summary:
Choice A is incorrect because a second exposure to an allergen does not cause the immune system to target self-antigens, which is the hallmark of autoimmune disorders. Choices B, C, and D are more plausible mechanisms for the development of autoimmune disorders.
Terminal deoxynucleotidyl transferase catalyzed reactions produce fragments with
- A. poly A or poly C tails
- B. poly C tails
- C. poly A tails
- D. poly A or poly T tail
Correct Answer: A
Rationale: Terminal deoxynucleotidyl transferase (TdT) adds nucleotides to the 3' end of DNA fragments in a template-independent manner. This results in the production of fragments with poly A or poly C tails. TdT does not add poly T tails, making option D incorrect. It also does not specifically add only poly C tails (option B) or poly A tails (option C). The addition of poly A or poly C tails by TdT is essential for techniques like DNA sequencing and PCR, where these tails are utilized for downstream applications.
Why don't we have a successful HIV vaccine?
- A. The high mutation rate of HIV interferes with the generation of a protective memory response
- B. Because it is difficult to induce mucosal immunity that would block the sexual transmission of the virus
- C. Because HIV targets immune cells
- D. All of the above represent challenges for the creation of an effective HIV vaccine
Correct Answer: D
Rationale: The correct answer is D because all the statements in choices A, B, and C are valid reasons why we don't have a successful HIV vaccine.
A: HIV has a high mutation rate, making it challenging to generate a protective memory response.
B: Inducing mucosal immunity is difficult to block sexual transmission, a common route of HIV infection.
C: HIV targets immune cells, which hinders the immune system's ability to mount an effective response.
Therefore, all these factors combined pose significant challenges for creating an effective HIV vaccine.