细胞倍增时间计算器 — 公式
## DNA Melting Temperature
The melting temperature (Tm) is the temperature at which 50% of double-stranded DNA molecules are denatured into single strands.
### Wallace Rule (for short oligos < 20 bp)
**Tm = 2(A+T) + 4(G+C)** °C
### Marmur-Doty (for longer DNA)
**Tm = 64.9 + 41 × (G+C - 16.4) / N** °C
GC base pairs have three hydrogen bonds (vs two for AT), making them more thermally stable.
The melting temperature (Tm) is the temperature at which 50% of double-stranded DNA molecules are denatured into single strands.
### Wallace Rule (for short oligos < 20 bp)
**Tm = 2(A+T) + 4(G+C)** °C
### Marmur-Doty (for longer DNA)
**Tm = 64.9 + 41 × (G+C - 16.4) / N** °C
GC base pairs have three hydrogen bonds (vs two for AT), making them more thermally stable.
计算示例
A 20-mer with 10 GC bases and 10 AT bases.
- AT count = 20 - 10 = 10
- Wallace: Tm = 2(10) + 4(10) = 20 + 40 = 60°C
- GC content = 10/20 × 100 = 50%