Question

The area of the gold electrodes on the quartz crystal microbalance at the opening of Chapter 2 is 3.3 mm^2. 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

Answer 1

To calculate the mass of cytosine bound to the surface of the electrode, multiply the surface density of the DNA by the area of the electrode. Then, multiply the result by the mass of cytosine per DNA molecule. The mass of cytosine bound to the electrode is approximately 4.4 x 10^-11 g.

Step-by-step explanation:

To calculate the amount of cytosine (C) bound to the surface of the electrode, we first need to calculate the number of DNA molecules on the surface. We can do this by multiplying the surface density of the DNA (1.2 pmol/cm²) by the area of the electrode (3.3 mm² = 0.33 cm²).

Number of DNA molecules = Surface density of DNA x Area of electrode = 1.2 pmol/cm² x 0.33 cm² = 0.396 pmol

Next, we need to calculate the mass of the nucleotide cytosine (C) in one DNA molecule. The molecular weight of cytosine is approximately 111.1 g/mol. Assuming one unit of cytosine is added to each DNA molecule when it is elongated, the mass of cytosine bound to the electrode is:

Mass of cytosine = Number of DNA molecules x Mass of cytosine per DNA molecule = 0.396 pmol x (111.1 g/mol / 10^12 pmol) = 4.4 x 10^-11 g

Answer 2

This question is incomplete, the complete question is;

The area of the gold electrodes on the quartz crystal microbalance at the opening of Chapter 2 is 3.3 mm^2. 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 mass formula mass of the bound nucleotide is cytosine + deoxyribose + phosphate = C9H10N3O6P = 287.2 g/mol

Answer: mass of the nucleotide (c) bound is 11.37 g

Step-by-step explanation:

Given that the area of gold electrodes = 3.3 mm^2

surface density of one gold electrode = 1.2 pmol/cm^2

that is to that in every 1 cm^2 of area, 1.2 pmol DNA is present

therefore

mass of nucleotide present in 3.3 mm^2 is;

= (1.2/100 * 3.3) pmol

= 0.0396 pmol

we were given that formula mass of the bound nucleotide = 287.2 g/mol

so

mass of the nucleotide (c) bound = ( 287.2 * 0.0396 )g

mass of the nucleotide (c) bound = 11.37 g