Which molecule is arranged as a double helix?

Which molecule is arranged as a double helix?

• A. DNA
• B. RNA
• C. Both DNA and RNA
• D. Neither

Answer: (A)

The double-helix arrangement is a defining feature of DNA. DNA is made of two long strands that run in opposite directions and coil around each other, held together by hydrogen bonds between complementary bases (A with T, G with C) and base-stacking interactions. This antiparallel, complementary pairing forms a stable, uniform helix with major and minor grooves, which is essential for accurate replication and transcription. RNA is typically single-stranded and folds into a variety of shapes to perform its functions; it can form local double-stranded regions, but it does not adopt the canonical long double helix seen in DNA. So the molecule arranged as a double helix is DNA.

The double-helix arrangement is a defining feature of DNA. DNA is made of two long strands that run in opposite directions and coil around each other, held together by hydrogen bonds between complementary bases (A with T, G with C) and base-stacking interactions. This antiparallel, complementary pairing forms a stable, uniform helix with major and minor grooves, which is essential for accurate replication and transcription.

RNA is typically single-stranded and folds into a variety of shapes to perform its functions; it can form local double-stranded regions, but it does not adopt the canonical long double helix seen in DNA. So the molecule arranged as a double helix is DNA.