試題詳解

25. The average molar mass of one base pair of nucleotides in DNA is approximately 600 g/mol. The spacing between successive base pairs is about 0.34 nm, and a complete turn in the helical structure of DNA occurs about every 3.4 nm. If a DNA molecule has a molar mass of 4.5 × 10⁹ g/mol, there are approximately _____ complete turns existing in the DNA a-helix structure.
(A) 5.2 × 10¹²
(B) 4.6 × 10⁹
(C) 8.0 × 10⁵
(D) 2.6 × 10⁶
(E) 9.4 × 10³