Regarding B-DNA answer the following Questions\ (A) Number of base pairs in a single helix is:\ (B

Question

Regarding B-DNA answer the following Questions\ (A) Number of base pairs in a single helix is:\ (B) Degree of rotation in B DNA between adjacent base pair is: \ (C) Diameter of DNA is ----- nm\

Professor PC Thomas Classes · Answer

In B - DNA, The backbone is formed by the sugar-phosphate-sugar chain. The nitrogen bases are projected more or less perpendicular to this backbone but face inside. A and G of one strand compulsorily base pairs with T and C , respectively, on the other strand. There are two hydrogen bonds between A and T. There are three hydrogen bonds between G and C. Each strand appears like a helical staircase. Each step of ascent is represented by a pair of bases. At each step of ascent, the strand turns $36^{\circ}$. One full turn of the helical strand would involve ten steps or ten base pairs. Attempt drawing a line diagram. The pitch would be $34 \AA$. The rise per base pair would be $3.4 \AA$. This form of DNA with the above mentioned salient features is called B-DNA.