Nokea
An essential cofactor for restriction endonuclease enzyme activity is
- A. Zn2+
- B. Mg2+
- C. Co2+
- D. Ca2+
Correct Answer: B
Rationale: The correct answer is B: Mg2+. Mg2+ is an essential cofactor for restriction endonuclease enzymes because it stabilizes the enzyme-substrate complex, promotes proper binding of the enzyme to DNA, and facilitates the catalytic activity of the enzyme. Mg2+ ions help in the coordination of the active site residues and the phosphate backbone of DNA, which is crucial for the cleavage of DNA strands. Zn2+, Co2+, and Ca2+ do not provide the necessary coordination and stabilization required for restriction endonuclease enzyme activity, making them incorrect choices.
You may also like to solve these questions
Select the correct number of statements that are true.
- A. Only 1 and 3 are correct.
- B. Only 2 and 4 are correct.
- C. Only 3 and 4 are correct.
- D. All of the above are correct.
Correct Answer: A
Rationale: The correct answer is A. Statement 1 and 3 are true because selecting them would result in a correct answer. Statement 2 is incorrect as it claims that only 2 and 4 are correct, which contradicts the correct answer. Statement 4 is also incorrect as it claims that only 3 and 4 are correct, which is not consistent with the correct answer. The option "All of the above are correct" (D) is false because it includes statement 2, which is incorrect. Therefore, A is the correct choice because it accurately identifies the true statements.
Your patient with rheumatoid arthritis (RA) is taking prednisone (Deltasone) and naproxen (Alleve) to reduce inflammation and joint pain. Which of these symptoms is the strongest indicator that a change in therapy may be necessary?
- A. The patient states that the RA symptoms are worst in the morning.
- B. The patient complains about having dry eyes.
- C. The patient has round and moveable nodules just under the skin.
- D. The patient has stools that are very dark in color.
Correct Answer: D
Rationale: Dark stools can indicate gastrointestinal bleeding which is a serious side effect of NSAIDs like naproxen. This requires immediate attention and possibly a change in therapy. The other symptoms while related to RA do not indicate an urgent need for a change in treatment.
What type of diseases does the immune system primarily defend against?
- A. Autoimmune diseases
- B. Infectious diseases
- C. Neurological disorders
- D. Cardiovascular diseases
Correct Answer: B
Rationale: The correct answer is B: Infectious diseases. The immune system's main function is to protect the body from foreign invaders such as bacteria, viruses, and parasites. It recognizes and eliminates these pathogens to prevent infections. Autoimmune diseases (A) occur when the immune system mistakenly attacks healthy cells. Neurological disorders (C) and cardiovascular diseases (D) are not primarily defended against by the immune system as they are not caused by external pathogens.
The physician is having difficulty finding the appropriate dose for the patient taking warfarin (Coumadin). What can the nurse suggest that may solve this problem?
- A. Pharmacogenetic testing
- B. Start bivalirudin (Angiomax) IV
- C. Change from warfarin (Coumadin) to clopidogrel (Plavix) and aspirin
- D. Change from warfarin (Coumadin) to enoxoparin (Lovenox) injections
Correct Answer: A
Rationale: Pharmacogenetic testing evaluates genetic variations affecting drug metabolism, helping optimize dosing for medications like warfarin.
What is not true about Salmonella thyphimurium?
- A. It is the causal agent of "hamburger disease"
- B. It is the second most common cause of food poisoning
- C. It is able to induce its own uptake by manipulating the actin cytoskeleton of host cells
- D. It is able to survive inside the phagosomes by manipulating the host actin cytoskeleton
Correct Answer: A
Rationale: The correct answer is A: It is the causal agent of "hamburger disease." Salmonella typhimurium is not the causal agent of "hamburger disease." Instead, Escherichia coli O157:H7 is the primary causal agent of this particular foodborne illness. Salmonella typhimurium is commonly associated with causing salmonellosis. Therefore, choice A is incorrect. Choices B, C, and D are all true statements about Salmonella typhimurium. It is the second most common cause of food poisoning, it is able to induce its own uptake by manipulating the actin cytoskeleton of host cells, and it is able to survive inside the phagosomes by manipulating the host actin cytoskeleton.