Question

Which diagram correctly labels the structure of DNA?

Radio button to select the answer below
A.


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B.


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C.


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D.

Answer 1

I can’t see the diagrams you’re choosing between. Please upload the images or type each option’s labels/description and I’ll pick the correct one.

Meanwhile, here’s a quick checklist to identify the correctly labeled DNA structure:

- Double helix made of two strands twisted around each other (not single-stranded).
- Sugar‑phosphate backbone is on the outside of the helix; phosphates and deoxyribose sugars alternate.
- Nitrogenous bases (A, T, G, C) are on the inside, pairing across the two strands.
- Complementary base pairing: A pairs with T (two hydrogen bonds), G pairs with C (three hydrogen bonds).
- The two strands are antiparallel: one runs 5′ → 3′, the other runs 3′ → 5′. The 5′ end has a free phosphate on the 5′ carbon of deoxyribose; the 3′ end has a free hydroxyl on the 3′ carbon.
- Phosphodiester bonds link the 3′ carbon of one sugar to the 5′ phosphate of the next nucleotide.
- Major and minor grooves are visible between the turns of the helix (optional detail).

If any diagram shows bases on the outside, single strand, uracil instead of thymine, or labels ribose instead of deoxyribose, it’s incorrect. Upload the images or describe them and I’ll tell you which choice (A–D) is correct.