This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'What will happen to DNA if salt is added to it? \nSelect and explain. \nA. Increase melting point (Tm), B. Decrease Tm, C. Not affect Tm, D. Melting lead to denaturation of DNA', 'role': 'user'}, {'content': 'Answer: A \nExplanation: This makes the DNA less hydrophilic (less soluble in water). Ethanol has a lower dielectric constant than water so it&;s used to promote ionic bonds between the Na+ (from the salt) and the PO3- (from the DNA backbone) causing the DNA to precipitate.', 'role': 'assistant'}]