| Base composition | Ratio | ||||||
|---|---|---|---|---|---|---|---|
| Source of DNA |
A | T | G | C | A/T | G/C | (A + G)/ (T + C) |
| E. coli | 26.0 | 23.9 | 24.9 | 25.2 | 1.09 | 0.99 | 1.04 |
| Yeast | 31.3 | 32.9 | 18.7 | 17.1 | 0.95 | 1.09 | 1.00 |
| Sea urchin | 32.8 | 32.1 | 17.7 | 18.4 | 1.02 | 0.96 | 1.00 |
| Rat | 28.6 | 28.4 | 21.4 | 21.5 | 1.01 | 1.00 | 1.00 |
| Human | 30.3 | 30.3 | 19.5 | 19.9 | 1.00 | 0.98 | 0.99 |
|
*Percentage in moles of nitrogenous constituents per 100 g- |
|||||||