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One turn of the helix in a B-form DNA is approximately -
A
20 nm
B
0.34 nm
C
3.4 nm
D
2 nm
Detailed Solution
B-DNA is the right-handed double helix described by Watson and Crick.
The distance between two successive base pairs is 0.34 nm.
There are roughly 10 base pairs in each complete turn of the helix.
So the pitch of the helix, i.e. the length of one turn, is 10 x 0.34 nm = 3.4 nm.
The diameter of the helix is 2 nm (20 Å).
So 0.34 nm is the rise per base pair and 2 nm is the width; one turn of the helix is approximately 3.4 nm.
The distance between two successive base pairs is 0.34 nm.
There are roughly 10 base pairs in each complete turn of the helix.
So the pitch of the helix, i.e. the length of one turn, is 10 x 0.34 nm = 3.4 nm.
The diameter of the helix is 2 nm (20 Å).
So 0.34 nm is the rise per base pair and 2 nm is the width; one turn of the helix is approximately 3.4 nm.