Question

TMV contains:
A)DNA
B)RNA + Protein
C)DNA + RNA
D)DNA + Protein

Answer 1

Hint: TMV refers to Tobacco Mosaic Virus. It is an RNA virus which infects plants such as tomato and tobacco. TMV is a positive-sense single-stranded virus.

Complete answer:
Viruses can be broadly divided into enveloped and non-enveloped viruses. Non-enveloped viruses contain a core of genetic material which is surrounded by a protective coat made up of protein, this coat is known as capsid. Capsid is made up of similar protein subunits which are known as capsomeres. The genetic material of a virus can be either RNA or DNA. The genetic material can be: single stranded RNA, double stranded RNA ,single stranded DNA or double stranded DNA. Therefore, a virus is a nucleoprotein and the genetic material is infectious. In enveloped viruses, nucleic acid and capsid are enclosed by an envelope, which is derived from the host membrane, so the envelope has lipids and proteins from the host cell and it sometimes also includes viral glycoproteins.

TMV is a non-enveloped virus which has single stranded RNA as genetic material. In this virus, capsomeres are stacked around RNA in a helical structure.

Tobacco mosaic virus was the first virus to be discovered by a scientist named D.J. Ivanowsky, in 1892. He recognised that mosaic disease of tobacco plants was caused by certain microbes which were smaller than bacteria as they could not pass through bacteria-proof filters. Ivanowsly's work was confirmed later in 1898 by another scientist named M.W. Beijerinek, who showed that extracts from infected tobacco plants could cause infection in healthy plants and he called this fluid as Contagium vivum fluidum.

Hence, the correct answer is option (B)

Note: In general the viruses that infect plants have single stranded RNA, whereas the viruses that infect animals can have Double stranded RNA double stranded DNA or single stranded DNA.