Friday, 12 August 2011
Unbelievable - each of us has enough DNA to circle the Earth 4 million times.
This is how it works:
If stretched, DNA in a single cell will extend to 1.5 metres**
A cell is typically 10 microns (1 micron = 10-6 m) across
Volume of a cell is of the order of 10-15 m3
Consider a 100 kg man with density equal to that of water (1000 kg/m3)
Volume of the person is 0.1 m3 (volume = mass/density)
Therefore, there are 1014 cells - this is 100,000 billion cells and
the length of the DNA is 150 billion km
This is sufficient to circle the Earth 4 million times!
** Human Genome Project has mapped 3 billion base-pairs in a human DNA. If base-pairs are 0.5 nm apart then the stretched DNA would be 1.5 m long.
Earth's circumference is about 40,000 km