DNA is isolated from a virus and found to contain 27 A 27 T

DNA is isolated from a virus and found to contain 27% A, 27% T, 23% C and 23% G. The DNA is likely to be:

a. contaminated with RNA.

b. circular.

c. single stranded.

d. double stranded.

Solution

Chargaff\'s rule for the DNA states that in any cell of an organism, the DNA will have 1:1 ratio of pyrimidine and purines. It specifically means that amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in the double-stranded DNA.

27% A, 27% T, 23% C and 23% G , means that this DNA is double stranded. This is referred to as first parity rule where double-stranded DNA molecule has percentage base pair equality.