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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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At the physiological pH the DNA molecules are:
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The correct answer is  DNA molecules are negatively charged. Histones, along with positively charged ions such as Mg2+, help neutralize the negatively charged DNA phosphate groups. Histone proteins possess an unusually high content of basic amino acids (arginine and lysine) that, through ionic bonds, facilitate interaction with the negatively charged DNA. Ref: Biochemistry By Richard A. Harvey (Ph. D.), Richard A. Harvey, Denise R. Ferrier, 2011, Page 409.