Salient features of DNA double helix (i) It is made up of two polynucleotide chains containing the backbone of sugar- phosphate and the bases project inside. (ii) The two chains have anti-parallel polarity one of them is 5?-»3?, the other has 3?-* 5? polarity. (iii) The bases in two strands are paired through hydrogen bond (H—bonds) forming base pairs (bp). Adenine pairs through two hydrogen bonds with thymine from opposite strand and vice-versa. In the same way, guanine is bonded with cytosine through three H—bonds. Due to which, purine always comes opposite to a pyrimidine. (iv)The two chains are coiled in a right-handed fashion. The pitch of the helix is 3.4 nm and there are roughly 10 bp in each turn. Consequently, the distance between base pair in a helix is about 0.34 nm. (v)The plane of one base pair stacks over the other in double helix. This confers stability to the helical structure
List the salient features of double helix structure of DNA.
Answers
Doshi
Salient features of DNA double helix
(i) It is made up of two polynucleotide chains containing the backbone of sugar- phosphate and the bases project inside.
(ii) The two chains have anti-parallel polarity one of them is 5?-»3?, the other has 3?-* 5? polarity.
(iii) The bases in two strands are paired through hydrogen bond (H—bonds) forming base pairs (bp). Adenine pairs through two hydrogen bonds with thymine from opposite strand and vice-versa. In the same way, guanine is bonded with cytosine through three H—bonds. Due to which, purine always comes opposite to a pyrimidine.
(iv)The two chains are coiled in a right-handed fashion. The pitch of the helix is 3.4 nm and there are roughly 10 bp in each turn. Consequently, the distance between base pair in a helix is about 0.34 nm.
(v)The plane of one base pair stacks over the other in double helix. This confers stability to the helical structure