In the 1940s, Chargaff and his co-workers analysed the base composition of the DNA of various organisms. The relative numbers of the bases adenine (A), cytosine (C), guanine (G) and thymine (T) of three of these organisms are shown in the table.

Explain why:

a. The relative numbers of each base in ox spleen and thymus are the same, within experimental error [2]

b. The relative numbers of each base in yeast are diff erent from those in ox spleen or thymus [2]

c. The relative numbers of the bases A and T, or of C and G, are similar in ox and yeast [2]

d. In the virus, the relative numbers of A and T, and of C and G, are not similar.

Transcribed Image Text:

Relative numbers of bases Organism (tissue) A T ox (spleen) ox (thymus) yeast virus with single-stranded DNA 27.9 20.8 22.7 27.3 28.2 21.2 21.5 27.8 31.3 17.1 18.7 32.9 24.3 18.2 24.5 32.3