Nokea
The HIV protein that allows fusion of the viral envelope with the cell plasma membrane is
- A. gp120
- B. gp41
- C. gp160
- D. CXCR4
Correct Answer: B
Rationale: The correct answer is B: gp41. Gp41 is responsible for the fusion of the viral envelope with the cell plasma membrane by undergoing conformational changes that allow the viral and cellular membranes to merge. Gp120 attaches to the host cell receptor (CD4), facilitating the binding of the virus to the host cell. Gp160 is the precursor protein that is cleaved into gp120 and gp41 during viral maturation. CXCR4 is a cellular co-receptor used by some strains of HIV to enter host cells but is not directly involved in the fusion process.
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The primary mode of treatment for ankylosing spondylitis is:
- A. Relaxed posture for comfort.
- B. Strict bed rest.
- C. Physical therapy.
- D. Respiratory therapy.
Correct Answer: C
Rationale: Physical therapy is the primary mode of treatment for ankylosing spondylitis as it helps maintain joint mobility and flexibility. While respiratory therapy may be beneficial in some cases, physical therapy addresses the core issues related to stiffness and pain.
To which cellular location would you expect NFkB to move in macrophages that have been stimulated with LPS?
- A. To the cytoplasm
- B. To phagosomes
- C. To the nucleus
- D. To the cell membrane
Correct Answer: C
Rationale: The correct answer is C: To the nucleus. When macrophages are stimulated with LPS, NFkB is activated and translocates to the nucleus. In the nucleus, NFkB regulates the expression of genes involved in the inflammatory response. Choices A, B, and D are incorrect because NFkB does not primarily move to the cytoplasm, phagosomes, or cell membrane in response to LPS stimulation in macrophages.
The Ig class found in breast milk is
- A. IgA
- B. IgM
- C. IgD
- D. IgG
Correct Answer: A
Rationale: The correct answer is A: IgA. IgA is found in breast milk and plays a crucial role in providing immunity to the infant. It helps protect against infections in the digestive and respiratory tracts. IgM is primarily found in the bloodstream, IgD is mainly on the surface of B cells, and IgG is transferred from the mother to the fetus during pregnancy. IgA is the specific immunoglobulin class present in breast milk, making it the correct choice.
All of the following are true with respect to IgM antibodies EXCEPT which one
- A. they fix complement
- B. they occur on the surface of lymphocytes
- C. they predominate in the primary response to antigen
- D. mediate allergic reactions
Correct Answer: D
Rationale: The correct answer is D. IgM antibodies do not mediate allergic reactions. IgE antibodies are responsible for allergic reactions. IgM antibodies fix complement, occur on the surface of lymphocytes, and predominate in the primary response to antigens. IgM is the first antibody produced in response to an infection, playing a key role in the activation of the complement system. IgM antibodies are mainly found in the blood and lymphatic system, not on the surface of lymphocytes. IgE antibodies are the primary mediators of allergic reactions by triggering the release of histamine and other inflammatory molecules.
What is a characteristic feature of Goodpasture's syndrome?
- A. Granuloma formation
- B. Pulmonary hemorrhage and glomerulonephritis
- C. Contact dermatitis
- D. Bronchoconstriction and vasodilation
Correct Answer: B
Rationale: The correct answer is B: Pulmonary hemorrhage and glomerulonephritis. Goodpasture's syndrome is an autoimmune disease characterized by the presence of anti-glomerular basement membrane antibodies, leading to damage in the kidneys (glomerulonephritis) and lungs (pulmonary hemorrhage). Granuloma formation (A), contact dermatitis (C), and bronchoconstriction and vasodilation (D) are not characteristic features of Goodpasture's syndrome. Granulomas are more commonly seen in conditions like sarcoidosis, contact dermatitis is an inflammatory skin condition, and bronchoconstriction and vasodilation are features of allergic reactions or asthma, not typically seen in Goodpasture's syndrome.