A-DNA

A type DNA is a right-handed, double helical structure of the DNA molecule. It has a wider and shorter helix than the more common B type DNA. A type DNA is found in specific biological contexts, such as in certain RNA-DNA hybrid structures and in chromatin remodeling.

B-DNA

B type DNA is the most common double helical structure of the DNA molecule. It has a narrow and longer helix than the A type DNA. B type DNA is the most stable form and is the basis for most of the DNA structures found in living organisms.

Z-DNA

Z type DNA is a left-handed double helical structure of the DNA molecule. It is more elongated and thinner than the A and B forms. Z DNA is found in certain DNA sequences and is involved in gene regulation and expression.