Question

Which of the following statement is incorrect about the following diagram?

• A. Capsomere are arranged in helical form
• B. Passes non-infectious RNA
• C. Proteins are the main component of the crystals
• D. It is the first virus to be discovered

Answer 1

Answer: (B)

↵ Tobacco mosaic virus is the best-known and most thoroughly studied plant virus. It was discovered by D. Ivanowski (1892) and crystallized by W. M. Stanley (1935). It was the first virus to be discovered.
TMV is rod-shaped, measuring approximately 3000Å in length and 180Å in diameter; total molecular weight being 39.4×10⁶. It is made up of RNA and proteins.
TMV having a central core of ssRNA as genetic material which is infectious surrounded by protein coat (capsid) to form the nucleocapsid. The nucleocapsid may be naked or maybe surrounded by a loose membranous envelope. It is composed of a number of subunits called capsomeres. The protein coat (capsid) consists of 2130 identical subunits (capsomeres). The protein is 94% and RNA is only 6%. In the entire length, a single RNA molecule runs in the form of spiral coils.
TMV infects a wide range of plants, especially tobacco and other members of the family Solanaceae.