Video Transcript
In a single human body cell, if the
chromosomes were uncoiled, stretched out, and laid end to end, approximately, how
long would this strand of DNA be? (A) 20 meters, (B) two meters, (C)
two centimeters, (D) two nanometers, (E) two millimeters.
The DNA in a human body cell is
contained in the nucleus. This DNA is organized into 23 pairs
of chromosomes or 46 chromosomes in total. If we unravel a single chromosome,
we can see that each chromosome is a tightly wound-up molecule of DNA.
Each DNA molecule is made up of
repeating subunits called nucleotides, and each nucleotide is 0.34 nanometers
long. In total, over the 46 chromosomes,
there is about six billion nucleotides. So, if we multiply six billion by
0.34 nanometers, we get 2.04 meters. This is how long all the DNA would
measure in a single human body cell.
Therefore, the correct answer is
(B), two meters.
