Question

A new virus has been discovered in a species of bacteria that inhabit hot springs. The viral genome is found to consist of four ribonucleotides in the following ratios: 8% A, 42% C, 42% G, and 8% U. The genome is made of:

a. double-stranded DNA
b. double-stranded RNA
c. single-stranded DNA
d. single-stranded RNA

Answer 1

The viral genome with equal ratios of C to G and A to U is most likely double-stranded RNA, reflecting the base pairing found in RNA double helices.

Step-by-step explanation:

Based on the given ribonucleotide ratios in the viral genome (8% A, 42% C, 42% G, and 8% U), we can conclude that the genome is likely to be double-stranded RNA rather than DNA. The presence of Uracil (U) instead of Thymine (T) indicates that the genetic material is RNA, not DNA. Furthermore, because the percentages of C and G are equal, as are the percentages of A and U, this suggests that the RNA is double-stranded, reflecting the RNA base pairing rules where A pairs with U and C pairs with G in a RNA double helix.

Viral genomes can be very diverse. Some viruses, like rhinoviruses and influenza, are known to have single-stranded RNA genomes. However, an equal percentage match between nucleotides associated with base pairing indicates a double-stranded structure. Therefore, the characteristics of this newly discovered viral genome do not correspond with typical single-stranded RNA viruses. Considering this information, we determine that the genome is not double-stranded DNA, single-stranded DNA, or single-stranded RNA.