Correct option is B
Correct Answer: (2) A, and B DNA helices are right-handed, Z DNA helix is left-handed.
Explanation:
A-DNA and B-DNA are both right-handed helices. B-DNA is the most common form under physiological conditions, while A-DNA typically forms under dehydrated conditions.
Z-DNA, in contrast, is a left-handed helix. It forms under specific conditions such as high salt concentrations or supercoiling stress, and it plays a potential role in biological processes like gene regulation.
Information Booster:
A-DNA is a right-handed helix, formed under conditions of dehydration, with 11 base pairs per turn.
B-DNA is the predominant form of DNA in vivo, exhibiting a right-handed helix with approximately 10.5 base pairs per turn.
Z-DNA is a left-handed helix with 12 base pairs per turn. It forms under specific conditions, such as negative supercoiling.
Z-DNA is thought to be involved in gene regulation and transcription processes, although its exact biological function remains under research.
A-DNA and B-DNA are critical for most biological functions, such as replication and transcription.
The structure of Z-DNA is significantly different from A and B forms, with a zigzag backbone instead of the usual double helix.
Additional Information:
Option 1: A, B, and Z DNA helices are left-handed. This is incorrect because A-DNA and B-DNA are right-handed, while only Z-DNA is left-handed.
Option 3: A, and Z DNA helices are left-handed, B DNA helix is right-handed. This statement is incorrect as A-DNA is right-handed under standard conditions, and only Z-DNA is left-handed.
Option 4: A, and B DNA helices are left-handed, Z DNA helix is right-handed. This is incorrect because A and B-DNA are both right-handed, while Z-DNA is left-handed.
