DNA’s sugar-phosphate backbones carry four kinds of bases. Complementary pairing links A with T and C with G. The sequence on one strand therefore helps determine the aligned sequence on the other. This supports copying. Real strands run in opposite chemical directions, which the end labels in the model make explicit.
The human body · Discover & try
How does DNA pairing help preserve information?
Reading level 3 of 5 · IndependentChange
Word help
Base pair
Two complementary DNA bases across the strands.
Complementary
Matching according to the A–T and C–G pairing rules.
Watch · Try · Explain
See how it works
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A flattened three-base model with explicit opposite strand directions. Compare aligned pairing with the direction used to read a strand.
What to look for
- Match one rung at a time.
- Compare the two strand-direction labels.
Explain what you noticed
In an aligned diagram, the top bases read C C A from left to right. Which bases sit directly below them?
Keep this idea: A pairs with T and C with G; strand orientation also matters.
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