Pick each base so the strand folds back on itself into exactly the right shape.
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How to play
Set the bases along an RNA strand so it folds into the target shape. Pairing follows the rules A with U and G with C, so the bases you choose decide which parts of the strand bond and how it folds.
Set each position to A, U, G or C
Remember A pairs U and G pairs C when the strand folds
Match the target fold shape to solve the puzzle
Harder levels use longer strands and trickier folds
Game modes
Easy, Medium or Hard difficulty
Daily puzzle or Practice for fresh strands
Controls
Desktop: click a base to cycle A to U to G to C, or use arrow keys to move and A/U/G/C to set
Phone & tablet: tap a base to cycle it through the four options
Tips & strategy
Work out which positions must pair in the target fold, then make those bases complementary
Place the stems (paired regions) first; loops are the leftover bases
If the fold is wrong, check for a mismatched pair before changing everything
What you'll learn
Strands is a molecular-biology puzzle about RNA base pairing and folding, building intuition for how nucleic acids form their shapes.
Skills: molecular biology, RNA, base pairing, nucleic acid structure
Best for: roughly grades 9–12 (ages 14+)
For parents & teachers: hands-on practice with base-pairing rules.
Origins
Choosing bases so an RNA strand folds into a target shape is base pairing: A with U, G with C, and the pairing decides which parts of the strand bond to which.
Designing the sequence to produce a shape is the original inversion.
That is the direction real RNA design works. The sequence is one-dimensional and the structure it produces is not, so a molecule's shape is encoded in its letters — which is why a single substitution can change what it does.
About Strands
Strands is a molecular-biology puzzle about RNA base pairing and folding. It's an original, free browser game built in-house for PlayPendium.
A free, original browser game on PlayPendium. No download, no install.
