The DNA molecule's shape is described as the twisted ladder. What is this shape called?

The DNA molecule's shape is described as the twisted ladder. What is this shape called?

• A. Single helix
• B. Double helix
• C. Triple helix
• D. Circular form

Answer: (B)

The twist described as a twisted ladder is the double helix. DNA is made of two long strands that run in opposite directions and pair up like rungs on a ladder, with the sugar-phosphate backbones on the outside. Base pairing between adenine and thymine, and between cytosine and guanine, holds the two strands together through hydrogen bonds, giving the ladder its stability as it twists into a helix. This two-strand, ladder-like arrangement is what gives DNA its familiar double helix shape. A single helix would have only one strand, a triple helix would need three strands, and circular form refers to topology rather than the two-stranded ladder structure.

The twist described as a twisted ladder is the double helix. DNA is made of two long strands that run in opposite directions and pair up like rungs on a ladder, with the sugar-phosphate backbones on the outside. Base pairing between adenine and thymine, and between cytosine and guanine, holds the two strands together through hydrogen bonds, giving the ladder its stability as it twists into a helix. This two-strand, ladder-like arrangement is what gives DNA its familiar double helix shape. A single helix would have only one strand, a triple helix would need three strands, and circular form refers to topology rather than the two-stranded ladder structure.