One turn of the helix in a Bform DNA is approximately - Vidyadip

MCQ

One turn of the helix in a Bform $DNA$ is approximately

A
$2\ nm$
B
$20\ nm$
C
$0.34\ nm$
✓
$3.4\ nm.$

✓

Answer

Correct option: D.

$3.4\ nm.$

d
(d) : $DNA$ or deoxyribose nucleic acid is the largest macromolecule made of the helically twisted two antiparallel polydeoxyribonucleotide strands held together by hydrogen bonds. The two strands of $DNA$ are together called $DNA$ duplex. It has a diameter of $20\ Å$. One turn spiral has a distance of $34\ Å$. It contains $10$ deoxyribonucleotides in each strand so that the distance between two adjacent nucleotides is $3.4\ Å$.

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