Question

If the length of a double helical $DNA$ is $1.7$ meters, then the number of base pairs present in the $DNA$ is

• A. $5\times 10^9$
• B. $1.7\times 10^9$
• C. $3.4\times 10^9$
• D. $1.7\times 10^5$

Answer 1

Answer: (A)

The structure of DNA is a double-helical structure.
The distance between two base pairs is 0.34nm.
Total length of double helix DNA = total number of base pairs $\times$ Distance between two base pairs.
Let us assume total number of base pair to be y.
$1.7m=y\times 0.35\times 10^{6}y=0.3\times 10^6÷1.7=5\times 10^9$
The number of base pairs present in DNA is 5 $\times$ 10⁹.