Question

Which of the following shows coiled RNA stands and capsomeres
A. Tobacco mosaic virus
B. Measles virus
C. Retrovirus
D. Poliovirus

Answer 1

Hint:- The tobacco mosaic virus is a single-stranded (positive) RNA virus. Measles virus is a negative-stranded RNA virus. It belongs to the paramyxoviridae family. Poliovirus is an enterovirus belonging to the picornaviridae family. It is single-stranded (positive). Retrovirus has RNA as its genome. This RNA is converted into DNA inside the host.

Complete answer:
Measles virus, retrovirus, and poliovirus do not have coiled RNA as their genome. The tobacco mosaic virus belongs to the Virgaviridae family and tobamovirus class. It is rod-shaped. It is protected by the capsid. The capsid is a protein coat that protects the viral genome. The capsid is made up of capsomeres. Capsomeres are the basic units of the capsids. The capsid of the tobacco mosaic virus contains about 2130 capsomeres. The capsomeres arrange themselves around the genome in such a way that it takes the shape of a hairpin. The genome of the tobacco mosaic virus is a single-stranded RNA that is coiled. The coiling is in a positive direction. The genome consists of 6400 base pairs.

So the correct answer is Option (A) - tobacco mosaic virus.

Note:- The tobacco mosaic virus is named so because it is found to infect the tobacco plant. Along with it, it also affects other plants belonging to the Solanaceae family. The term mosaic is used in its name because when it affects a plant, its leaves are discolored and moulted in a mosaic-like pattern. The tobacco mosaic virus can also affect plants like tomatoes and peppers.