Question

What is Z-dna and B-dna?

Answer 1

Z-DNA & B-DNA:

1. Z-DNA:
   1. Structurally differing, such a form of DNA is left-handed double helix.
   2. The helical width of the Z-DNA is 1.8 nm, making it narrowest compared to the other DNA conformations.
   3. Its distinguishing factor is its backbone appearing as though a zigzag.
   4. Each turn comprises 12 base pairs, 4.56 nm long.
   5. 2 adjacent deoxyribonucleotides are 0.37 nm apart with the presence of hydrogen bonds between 2 strands.
2. B-DNA:
   1. Commonly occurring DNA form in normal physiological conditions, this form of DNA is a right-handed double helix.
   2. The 2 strands of this DNA run in two different directions.
   3. They also show an asymmetrical structure, with the alternate presence of major and minor grooves.
   4. It is a result of glycosidic bonds of a base pair not being diametrically opposed to one another.
   5. Between adjacent deoxyribonucleotides, there is a distance of 0.34 nm & each turn comprises 10.5 base pairs of length 3.4 nm.
   6. The helical width of the B-DNA is 2 nm and its backbone generally comprises sugar phosphates associated continuously by phosphodiester bonds. The core comprises nitrogenous bases.