Nokea
DNA ligase catalyzes reactions that facilitate the formation of
- A. ester bonds
- B. DNA ligase
- C. phosphohydroxyl bonds
- D. amide bonds
Correct Answer: B
Rationale: DNA ligase catalyzes the formation of phosphodiester bonds between the sugar-phosphate backbone of DNA strands. The correct answer is B because DNA ligase specifically acts on these phosphodiester bonds to seal nicks in the DNA molecule during processes like DNA replication and repair. Option A, ester bonds, are not formed by DNA ligase. Option C, phosphohydroxyl bonds, is not a recognized type of bond in DNA ligation. Option D, amide bonds, are not formed by DNA ligase either. Thus, the correct answer is B as it aligns with the known function of DNA ligase.
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Mature naïve T cells that leave the thymus
- A. Are all tolerant to self-antigens because all self-reactive developing T cells have been killed in the thymus
- B. Might include some self-reactive T cells that have not been tolerized against a specific Ag
- C. Go first to LN where they acquire the ability to recognize antigen presented by MHC
- D. Go first to LN to be tested for self-reactivity
Correct Answer: B
Rationale: The correct answer is B because mature naïve T cells that leave the thymus can include self-reactive T cells that have not been tolerized against a specific antigen. This is because the process of negative selection in the thymus eliminates most self-reactive T cells but does not catch all of them. Some self-reactive T cells may escape negative selection and circulate as mature naïve T cells. Therefore, it is possible for mature naïve T cells leaving the thymus to include self-reactive T cells that have not been tolerized against a specific antigen.
Choices:
A: This is incorrect because although negative selection in the thymus eliminates most self-reactive T cells, it does not catch all of them, so some self-reactive T cells may still be present in the mature naïve T cell population.
C: This is incorrect because mature naïve T cells already have the ability to recognize antigens presented by MHC, which is developed in the th
Which cell type is a sentinel in the tissues and part of the innate immune system?
- A. T lymphocytes
- B. Dendritic cells
- C. B lymphocytes
- D. Plasma cells
Correct Answer: B
Rationale: The correct answer is B: Dendritic cells. Dendritic cells are sentinel cells in tissues that detect pathogens and activate the immune response. They are crucial in initiating adaptive immune responses by presenting antigens to T cells. T lymphocytes (A) are involved in adaptive immunity, not innate immunity. B lymphocytes (C) mature into plasma cells (D) which produce antibodies, but they are not sentinel cells in tissues like dendritic cells.
The patient is experiencing fibrosis and glomerulopathy a year after a kidney transplant. Which type of rejection is occurring?
- A. Acute
- B. Chronic
- C. Delayed
- D. Hyperacute
Correct Answer: B
Rationale: Chronic rejection occurs over time and involves fibrosis and structural changes in the transplanted organ.
Who accidentally identified the antimicrobial action of penicillin?
- A. Robert Koch
- B. Richard Petri
- C. Alexander Fleming
- D. Louis Pasteur
Correct Answer: C
Rationale: The correct answer is C: Alexander Fleming. Fleming discovered the antimicrobial action of penicillin in 1928 through his experiment with Staphylococcus bacteria. He noticed that mold from a contaminated petri dish inhibited the growth of the bacteria. Robert Koch (A) is known for his work in identifying specific bacteria causing diseases. Richard Petri (B) is not a known figure in the field of microbiology. Louis Pasteur (D) is famous for his germ theory and pasteurization, but he did not discover penicillin's antimicrobial action. Therefore, based on historical evidence and Fleming's specific contribution to microbiology, choice C is the correct answer.
A patient who has received a kidney transplant has been admitted to the medical unit with acute rejection and is receiving IV cyclosporine (Sandimmune) and methylprednisolone (Solu-Medrol). Which staff member is best to assign to care for this patient?
- A. An RN who floated to the medical unit from the coronary care unit for the day.
- B. An RN with 3 years of experience in the operating room who is orienting to the medical unit.
- C. An RN who has worked on the medical unit for 5 years and is working a double shift today.
- D. A new graduate RN who needs experience with IV medication administration.
Correct Answer: C
Rationale: An experienced RN who is familiar with the medical unit and its protocols is the best choice for caring for a patient with acute rejection. This patient requires close monitoring and skilled care which an experienced RN can provide. The other options involve RNs who may not be as familiar with the unit or are less experienced.