Question

Alcohol impairs both absorption and storage of folate, Megaloblastic erythropoicsis occurs because cells are arrested in the S phase since DNA synthesis is inhibited. DNA synthesis is inhibited in folate deficiency because tetrahydrofolate is required A. in the synthesis of purine nucleotides and dTMP. B. in the conversion of homocysteine to methionine. C. for the utilization of Vitamin B \(_{12}\) D. all of the above. E. none of the above.

Short answer

A. The synthesis of purine nucleotides and dTMP B. The conversion of homocysteine to methionine C. The utilization of Vitamin B12 D. All of the above Answer: D. All of the above

Step-by-step solution

Understand the role of Folate in DNA Synthesis

Folate plays a crucial role in DNA synthesis by providing active forms of tetrahydrofolate, which are needed for the synthesis of purine nucleotides and deoxythymidine monophosphate (dTMP), as well as the conversion of homocysteine to methionine. Vitamin B\(_{12}\) is also related to folate metabolism, as it is a cofactor in the conversion of 5-methyltetrahydrofolate to tetrahydrofolate.

Evaluate each option provided

A. "in the synthesis of purine nucleotides and dTMP": This statement is correct, as tetrahydrofolate is involved in the synthesis of both purine nucleotides and dTMP, which are essential for DNA synthesis. B. "in the conversion of homocysteine to methionine": This statement is also correct. Tetrahydrofolate, specifically its 5-methyl derivative, is involved in the conversion of homocysteine to methionine, which is a crucial step for the synthesis of S-adenosylmethionine, a methyl group donor for various reactions, including the synthesis of nucleic acids. C. "for the utilization of Vitamin B \(_{12}\)": This statement is partially correct. Although tetrahydrofolate is not directly involved in the utilization of vitamin B\(_{12}\), both folate and vitamin B\(_{12}\) are interacting in their metabolic pathways. Vitamin B\(_{12}\) acts as a cofactor in the conversion of 5-methyltetrahydrofolate to tetrahydrofolate, which is required for DNA synthesis.

Choose the correct answer

Based on the above evaluation of each statement, we can conclude that the correct answer is D. All of the above. As the role of tetrahydrofolate is involved in all of the mentioned processes, which are crucial for DNA synthesis.