DNA Double Helix coloring worksheet with structure diagram and descriptive writing section.

Final Answer:
The DNA double helix has two strands that run in opposite directions (antiparallel), with sugar-phosphate backbones on the outside and nitrogenous bases paired inside: adenine (A) with thymine (T) via 2 hydrogen bonds, and guanine (G) with cytosine (C) via 3 hydrogen bonds. The structure is stabilized by these base pairs and hydrophobic interactions.

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Explanation:
- DNA looks like a twisted ladder — that’s the “double helix.”
- The sides of the ladder are made of sugar and phosphate (the backbone).
- The rungs are made of paired bases: A always pairs with T, and G always pairs with C.
- A–T has 2 hydrogen bonds; G–C has 3 — so G–C pairs are stronger.
- The two strands go in opposite directions: one runs 5’→3’, the other 3’→5’ (this is called antiparallel).
- In the coloring part (not shown here), you’d color A–T pairs one color and G–C pairs another, based on the key.
- For the 5–7 sentence description: say what the shape is, what the parts are, how bases pair, and why the pairing matters (e.g., for copying DNA correctly).