Nokea
In reference to the flow diagram below respond to the following question. The annotation A refers to which sites
- A. Annealing
- B. Melting
- C. Restriction
- D. RNAse
Correct Answer: C
Rationale: The correct answer is C: Restriction. In a flow diagram, the annotation "Restriction" likely indicates the site where a DNA molecule is being cut by a restriction enzyme. This process is essential in molecular biology for DNA manipulation.
Choice A: Annealing involves the process of complementary DNA strands coming together, usually during PCR or hybridization.
Choice B: Melting refers to the separation of double-stranded DNA into single strands, often seen in denaturation steps.
Choice D: RNAse is an enzyme that specifically degrades RNA molecules, not involved in the DNA manipulation processes indicated in the diagram.
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Which of the following statements is most correct?
- A. MHC class I proteins typically bind to peptides from proteins taken up from outside the cell, and present these to CD8+ Tc cells
- B. MHC class I proteins typically bind to peptides from proteins made inside the cell, and present these to CD8+ Tc cells
- C. MHC class I proteins typically bind to peptides from proteins made inside the cell, and present these to CD4+ Th cells
- D. MHC class I proteins typically bind to peptides from proteins taken up from outside the cell, and present these to CD4+ Th cells
Correct Answer: B
Rationale: The correct answer is B. MHC class I proteins bind to peptides from proteins made inside the cell and present them to CD8+ Tc cells. This statement is correct because MHC class I proteins are responsible for presenting endogenous peptides, derived from proteins synthesized within the cell, to CD8+ Tc cells for immune surveillance and response.
Explanation for why other choices are incorrect:
- A is incorrect because MHC class I proteins present endogenous peptides, not peptides from proteins taken up from outside the cell.
- C is incorrect because MHC class I proteins present antigens to CD8+ Tc cells, not CD4+ Th cells.
- D is incorrect because MHC class I proteins present peptides to CD8+ Tc cells, not CD4+ Th cells.
What chemicals are responsible for the flavor and holes in Swiss cheese?
- A. lactate, oxygen
- B. propionic acid, carbon dioxide
- C. acetic acid, carbon dioxide
- D. ethanol, hydrogen
Correct Answer: B
Rationale: The correct answer is B: propionic acid, carbon dioxide. Propionic acid is produced by bacteria in Swiss cheese, contributing to its nutty flavor. The bacteria also produce carbon dioxide, which forms the characteristic holes. Lactate (A) is a byproduct of bacteria in cheese but not responsible for the flavor or holes. Acetic acid (C) is not commonly found in Swiss cheese. Ethanol (D) and hydrogen are not involved in the flavor or hole formation.
Polyclonal antibodies made in response to a given antigen will be:
- A. Derived from multiple B cell clones
- B. A mixture of different affinities
- C. A mixture of different antibody classes
- D. All options are correct
Correct Answer: D
Rationale: Step-by-step rationale for why Answer D is correct:
1. Polyclonal antibodies are produced by multiple B cell clones in response to an antigen (Choice A).
2. These antibodies have varying affinities due to the diversity of B cell clones involved (Choice B).
3. Different antibody classes, such as IgM, IgG, IgA, etc., are produced by different B cells (Choice C).
4. Therefore, all options are correct as polyclonal antibodies exhibit these characteristics.
The researcher that postulated the existence of 'pattern recognition receptors' on innate cells was:
- A. Susumu Tonegawa
- B. Ilya Metchnikoff
- C. Charles Janeway
- D. Ralph Steinman
Correct Answer: C
Rationale: The correct answer is C: Charles Janeway. He proposed the existence of pattern recognition receptors on innate cells in the 1980s, leading to the development of the concept of innate immunity. Janeway's hypothesis revolutionized our understanding of immune responses by emphasizing the role of pattern recognition in detecting pathogens. Tonegawa is known for his work on immune diversity; Metchnikoff discovered phagocytes; and Steinman identified dendritic cells. Janeway's contribution to immunology specifically focuses on pattern recognition receptors, making him the correct choice for this question.
What is the key immune cell involved in granuloma formation?
- A. Mast cells
- B. Macrophages
- C. Neutrophils
- D. Dendritic cells
Correct Answer: B
Rationale: The correct answer is B: Macrophages. Macrophages are key immune cells involved in granuloma formation. They play a crucial role in engulfing and processing pathogens or foreign particles, leading to the formation of granulomas as part of the body's immune response. Mast cells (A) are primarily involved in allergic reactions. Neutrophils (C) are important in the initial immune response to infections but are not typically associated with granuloma formation. Dendritic cells (D) are important in antigen presentation and activation of T cells, but they are not the primary immune cells involved in granuloma formation.