Question

A DNA molecule contains 10,000 base pairs, then the length of this DNA molecule is

• A. $3.4\times {10}^{-5}$ meter
• B. $0.34\times {10}^{-5}$ meter
• C. $34\times {10}^{-5}$ meter
• D. None of the above

Answer 1

The correct option is B $0.34\times {10}^{-5}$ meter

There are 10 base pairs per turn of the helical DNA and so the helix rises by 34 $\mathring{A}$ per turn.
As 10 base pairs = 34 $\mathring{A}$
So, 10,000 base pairs will be = (34 x 10000)/10 (Angstroms).
Since 1 Angstrom is 10${}^{-10}$ m.
So, the length of this DNA will be 0.34 x 10${}^{-5}$ m.