Question

For the structure of nucleic acid, which of the following statements is wrong?
A. DNA can be single stranded in some viruses.
B. RNA can be double stranded occasionally.
C. There are as many as 12 bases per turn in Z DNA.
D. The length of one helix is $45{\rm A}^\circ $ in B-DNA and in Z-DNA.

Answer 1

Hint: Biopolymers, or big macromolecules, such as nucleic acids are required for all known forms of life. They are made up of nucleotides, which are three-component monomers consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Complete answer:
The two strands of DNA are interwoven rather than parallel in a DNA molecule. Each strand has the appearance of a helix. The two strands create a "double helix" structure, which James D. Watson and Francis Crick initially discovered in 1953. The helix turns every 3.4 nm in this structure, commonly known as the B form, and the distance between two neighbouring base pairs is 0.34 nm.
As a result, each turn has around 10 pairs. The entangled strands form two grooves of varying widths, referred to as the major groove and minor groove, which may aid in protein binding. The DNA structure may shift to an A form in a solution with increased salt concentrations or alcohol added, which is still right-handed but turns every 2.3 nm and has 11 base pairs per turn.
The Z type of DNA is named from the way its bases appear to zigzag. Z DNA is a left-handed individual. One turn is 4.6 nm long and consists of 12 base pairs. In alcohol or a high salt solution, a DNA molecule with alternating G-C sequences has this structure.
One complete turn of the helix in Z-DNA is $45{\rm A}^\circ $ long, while it is $34{\rm A}^\circ $ in B DNA.
Therefore, the correct answer is option D.

Note: Nucleic acid is a type of macromolecule that can be present in all organisms and viruses. Nucleic acids are responsible for the storage and expression of genetic information. The information a cell needs to create proteins is encoded in deoxyribonucleic acid (DNA).