Double Helix 3D (DNA)
100%
A
T
G
C
N
Selected pair
Motif match
Scroll the helix · click any pair to inspect it
Pair 1 of 0
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Strand 1
5′ → 3′–—
5′ → 3′–—
Strand 2
3′ → 5′–—
3′ → 5′–—
MATCH—
Neighboring pairs — click a tile to jump
Helix Facts — B-DNA
- Rise: 3.4 Å per base pair
- Base pairs per turn: 10.5
- Pitch: 34 Å per full turn
- Diameter: 2.0 nm
- Handedness: right-handed double helix
- Strands: antiparallel (5′→3′ against 3′→5′)
- Major groove: 2.2 nm wide
- Minor groove: 1.2 nm wide
Pairing Rules
- A – T: 2 hydrogen bonds (weaker)
- G – C: 3 hydrogen bonds (stronger)
- Strand 1 runs 5′ → 3′; Strand 2 runs 3′ → 5′
- Each strand is the exact complement of the other