The diameter of a typical human cell nucleus is approximatel

The diameter of a typical human cell nucleus is approximately 6 m. Human chromosome 2 consists of approximately 243 million contiguous base pairs. Calculate the length of chromosome 2 if it were extended in a relaxed B-form structure. How does this compare with the diameter of the nucleus?

Solution

The accepted length of one base pair is 0.34 nm.

243 million base pairs = 243 000 000 base pairs

Therefore the length of the chromosome = 243 000 000 x 0.34 = 82 62 00 00 nm

Converting to cm = 8.262 cm.

The human cell nucleus is 6 micrometer = 0.0006 cm. Therefore the nucleus is at least a thousand times smaller than the length of the chromosome. Hence, the DNA is tightly packed using histone proteins to fit within the nucleus.