Question

The right-handed DNA form is
A. A and B
B. C and Z
C. Z and A
D. B and Z

Answer 1

Hint: Double-stranded and linked by interactions between complementary base pairs are three major types of DNA. These are A-form, B-form, and Z-form DNA concepts. A right-handed helix may be DNA. The most common type, present at neutral pH and physiological salt concentrations in most DNA, is the B-form. That is the classic double-helical structure, right-handed.

Complete step by step answer:
- B-form DNA: It could be a helix right-handed. It is the typical type of DNA that occurs under normal physiological conditions. B-DNA's double strands pass in opposite directions.
- A-DNA: Along with B-DNA and Z-DNA, A-DNA is known to be one of three biologically active double-helical structures. It's more like B-DNA, but with a structural organization that is shorter and more compact.
- C-DNA: It's one of all the different possible DNA double-helical structures. This form of DNA is not very stable and not very prevalent. This is the right-handed helix here.
- Z-DNA: Z-DNA is one of the many DNA double-helical structures that are possible. It is a double-helical left-handed structure in which the helix winds like the more typical B-DNA shape to the left in a zigzag pattern, instead of to the right.
So B-form DNA and A-form DNA are right-handed DNA forms.
Hence option A. A and B is the correct answer.

Note: Helices can be left-handed or right-handed. With the line of sight along the helix's axis, if the helix is shifted away from the observer by a clockwise screwing motion, then it is considered a right-handed helix; if it is a left-handed helix towards the observer.