A nucleus is 4 $\mu$m in diameter. Its DNA is composed of a million base pairs. Approximately how much does it need to be condensed in order to fit inside the nucleus?
A)30-fold
B)100,000-fold
C)1 million-fold
D)3 million-fold

Question

Quizplus · Accepted Answer

The volume of a sphere is proportional to the cube of its radius. Therefore, if the diameter of the nucleus is reduced by a factor of 3, the volume would be reduced by a factor of 27 (3^3). To fit a million base pairs of DNA within this reduced volume, the DNA must be condensed 27-fold (3^3) from its extended state, or 3 million-fold (27 x 100,000) from its fully relaxed state. Therefore, choice D, 3 million-fold, is the best answer.

A Nucleus Is 4 μ\muμ M in Diameter

A Nucleus Is 4 $\mu$ M in Diameter