Nokea
What lineage do natural killer (NK) cells belong to?
- A. Myeloid lineage
- B. Erythroid lineage
- C. Lymphoid lineage
- D. Granulocyte lineage
Correct Answer: C
Rationale: The correct answer is C: Lymphoid lineage. NK cells are a type of lymphocyte that is part of the innate immune system. They are derived from common lymphoid progenitors in the bone marrow. NK cells play a crucial role in recognizing and killing infected or abnormal cells. Myeloid lineage (A) gives rise to cells like macrophages and granulocytes, not NK cells. Erythroid lineage (B) produces red blood cells, and granulocyte lineage (D) gives rise to neutrophils, basophils, and eosinophils, not NK cells. Therefore, the correct choice is C as NK cells originate from the lymphoid lineage.
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The rearrangement of gene segments that occurs randomly in B cell receptor genes and T cell receptor genes:
- A. Occurs during clonal expansion of B cells and T cells
- B. Involves rapid genetic mutation after lymphocytes become activated
- C. Allows the mature lymphocyte population to recognize an enormous diversity of antigens
- D. Occurs in the DNA of all cells in the body
Correct Answer: C
Rationale: Step 1: Gene rearrangement in B cell and T cell receptor genes creates unique receptor proteins.
Step 2: This diversity allows mature lymphocytes to recognize a wide range of antigens.
Step 3: This process is crucial for adaptive immune response and antigen specificity.
Step 4: Choices A and B do not accurately describe gene rearrangement.
Step 5: Choice D is incorrect as gene rearrangement is specific to lymphocytes, not all cells in the body.
VDJ gene rearrangement takes place in
- A. Germinal Centers
- B. Lymph Nodes
- C. Bone marrow
- D. Spleen
Correct Answer: C
Rationale: Rationale: VDJ gene rearrangement occurs during lymphocyte development to generate diverse antigen receptors. This process occurs in the bone marrow, specifically in the early stages of B cell development. In the bone marrow, B cell precursors undergo VDJ recombination to create unique antibody specificity. Germinal centers are sites for B cell activation and proliferation, not gene rearrangement. Lymph nodes and spleen are secondary lymphoid organs where mature lymphocytes are activated, not where VDJ recombination occurs.
The annotation C refers to which DNA component?
- A. Vector DNA
- B. Plasmid DNA
- C. Chromosomal DNA
- D. Recombinant DNA
Correct Answer: C
Rationale: The correct answer is C: Chromosomal DNA. Chromosomal DNA refers to the DNA found in the chromosomes of an organism's nucleus, carrying the majority of its genetic information. In molecular biology, the annotation C typically refers to the chromosomal DNA of the organism being studied. Plasmid DNA (choice B) and vector DNA (choice A) are extrachromosomal DNA elements that are separate from the chromosomal DNA. Recombinant DNA (choice D) is a DNA molecule formed by combining DNA from different sources, which can include chromosomal, plasmid, or vector DNA. Therefore, the correct choice is C as it specifically refers to the chromosomal DNA component.
Monoclonal antibodies can be used to:
- A. Block the proliferation of cancer cells
- B. Target cancer cells for destruction
- C. Inhibit inflammatory immune responses
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because monoclonal antibodies have the ability to block the proliferation of cancer cells by targeting specific antigens on the cancer cells. They can also target cancer cells for destruction through various mechanisms such as antibody-dependent cell-mediated cytotoxicity. Additionally, monoclonal antibodies can inhibit inflammatory immune responses by neutralizing pro-inflammatory mediators or blocking immune cell activation pathways. Therefore, all the options A, B, and C are correct, making D the correct answer.
During the course of an immune response to a given antigen, affinity maturation results in survival of:
- A. B cells whose secretion of antibody occurs at a higher rate
- B. B cells whose antibodies bind the antigen more strongly
- C. T cells whose TCRs bind the antigen more strongly
- D. Both B and C are correct
Correct Answer: B
Rationale: Rationale:
1. Affinity maturation is the process where B cells produce antibodies with increased affinity for the antigen over time.
2. B cells whose antibodies bind the antigen more strongly have higher affinity.
3. Survival of B cells with higher affinity antibodies is crucial for effective immune response.
4. A is incorrect as rate of antibody secretion doesn't necessarily correlate with affinity.
5. C is incorrect as T cells are not directly involved in affinity maturation of antibodies.
6. D is incorrect since T cells are not affected by affinity maturation in the context of this question.