If a DNA molecule in a cell were stretched out, its length would be about how long?

If a DNA molecule in a cell were stretched out, its length would be about how long?

• A. Three feet
• B. One meter
• C. One inch
• D. Six feet

Answer: (D)

DNA length in a cell demonstrates how a tiny nucleus can contain an enormous amount of genetic material. The human diploid genome has about 6.4×10^9 base pairs, and the DNA backbone extends about 0.34 nanometers per base pair along the helix. Multiply those together and you get roughly 2 meters of DNA per cell—about six feet. That is the magnitude scientists refer to when they say a single cell could stretch to about six feet if uncoiled. In reality, this long molecule is tightly packed into chromatin and chromosomes, so it fits in the tiny nucleus, but the potential length when extended is on the order of several feet. The other options are too short by noticeable amounts.

DNA length in a cell demonstrates how a tiny nucleus can contain an enormous amount of genetic material. The human diploid genome has about 6.4×10^9 base pairs, and the DNA backbone extends about 0.34 nanometers per base pair along the helix. Multiply those together and you get roughly 2 meters of DNA per cell—about six feet. That is the magnitude scientists refer to when they say a single cell could stretch to about six feet if uncoiled. In reality, this long molecule is tightly packed into chromatin and chromosomes, so it fits in the tiny nucleus, but the potential length when extended is on the order of several feet. The other options are too short by noticeable amounts.