Quartz crystal microbalance. The area of the gold electrodes on the quartz crystal microbalance at the opening of Chapter 2 is 3.3 mm². One gold electrode is covered with DNA at a surface density of 1.2 pmol/cm². 

(a) How much mass of the nucleotide cytosine (C) is bound to the surface of the electrode when each bound DNA is elongated by one unit of C? The formula mass of the bound nucleotide is cytosine 1 deoxyribose 1 phosphate 5 C₉H₁₀N₃O₆P 5 287.2 g/mol.

(b) The shift in quartz crystal oscillator frequency for binding of DNA to the gold electrode was found to be 210 Hz for each ng/cm²
bound to the electrode. Calculate how many ng of cytosine per square centimeter of electrode area are bound when the observed frequency change is 24.4 Hz. Is the frequency change consistent with the extension of DNA by one unit of C?