Consider a double-stranded DNA molecule with 109 base pairs. a. Calculate its length in meters. b. Determine the minimum volume needed to contain it.

a) 0.34 m

b) 1.0676 x 10⁻¹⁸m³

Explanation:

a.) In a DNA helix structure, each turns contains 10 base pairs, so the total number of turns in a DNA molecule with 10⁹ base pairs = 10⁹/10 = 10⁸ turns.

Ideally, in-between two consecutive base pairs, the distance is usually = 0.34nm or 0.34 x 10⁻⁹m

Therefore, the length of turns in a double-stranded DNA molecule can be calculated as:

10 x 0.34 x 10⁻⁹m = 3.4 x 10⁻⁹m

As such, for 10⁸ turns the total distance or length in meters = 10⁸ x 3.4 x 10⁻⁹m = 0.34 m

b.) In order to determine the minimum volume needed to contain this Double helical DNA, we require a space similar to a Cylinder. Hence, we need to calculate the volume of that cylinder which will be the minimum volume needed to contain it.

The distance between two-strand = 2nm = 2 x 10⁻⁹m (i. e this will represent the diameter of the cylinder)

the length represent the height of the cylinder

The volume of cylinder can then be calculated as = πr²h

= 3.14 x (1 x 10⁻⁹m) ² x 0.34 m

= 1.0676 x 10⁻¹⁸m³