Question

A double stranded DNA having 100,000 bp will have a length of

• A. 10,000 nm
• B. ${10}^5$ nm
• C. $3.4\times {10}^4$ nm
• D. 200,000 nm

Answer 1

Answer: (C)

$3.4\times {10}^4$ nm

• As we know that DNA is a double helix; one complete turn of the double helix is 3.4 nm long, each of which has 10 base pairs thus the distance between two consecutive base pairs is 3.4/10 = 0.34 nm.
• Therefore, double-stranded DNA having 100,000 bp will have a length of 0.34 x ${10}^5$ = 3.4 x ${10}^4$ nm.

Thus, the correct answer is C.