Class 12 Botany simulations · Molecular Basis of Inheritance

DNA double helix

Spin a B-DNA double helix, change its length and GC content, and calculate how long the molecule would be.

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What to notice

A human diploid cell has about 6.6 × 10⁹ bp — about 2.2 m of DNA if stretched out.

Key relation

Rise 0.34 nm per bp ; 10 bp per turn ; pitch 3.4 nm ; A = T and G = C (Chargaff)

Try this

Set the length to the human value (log₁₀ bp ≈ 9.8). How long is the DNA?

What you can change

• Length (log₁₀ base pairs): 1 to 10
• GC content: 20 to 80 %

More in Molecular Basis of Inheritance

• Transcription and translation
• DNA fingerprinting with VNTRs
• The lac operon
• Semiconservative replication (Meselson–Stahl)

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