| | | | | 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 |
| *Percent in moles of nitrogeneous constituents per 100 g-atoms of phosphate in hydrolysate corrected for 100% recovery. From E. Chargaff and J. Davidson (eds). The Nucleic Acids, Vol 1. (New York: Academic press, 1955) |
Table 10.1: Base composition (percent*) of DNA from different sources and ratios of bases