The analysis of the nitrogenous bases of the nucleic acid of a newly discovered virus showed 20% adenine, 40% guanine, 10% thymine, and 30% cytosine.The viral nucleic acid is most likely
A)double-stranded DNA.
B)double-stranded RNA.
C)single-stranded RNA.
D)single-stranded DNA.

Question

Quizplus · Accepted Answer

The percentages of adenine and thymine should be equal in a double-stranded DNA, but here adenine is only 20% and thymine is 10%. In a double-stranded RNA, adenine and uracil should be equal, but uracil is not present here. In a single-stranded RNA, the percentages of adenine and uracil should be equal, but uracil is not present here either. The percentages of guanine and cytosine are equal in both single-stranded RNA and single-stranded DNA, but adenine should be equal to thymine in single-stranded DNA, which is not the case here. Therefore, the viral nucleic acid is most likely single-stranded DNA.

The Analysis of the Nitrogenous Bases of the Nucleic Acid