Question

Which of the following is devoid of protein coat and entirely composed of RNA only?

• A. TMV
• B. Poxvirus
• C. PSTV
• D. Caulimo virus

Answer 1

The correct option is C PSTV

Poxvirus consists of a nucleoprotein core which contains double-stranded DNA coated by different types of proteins maintaining the DNA in its helical state.

TMV is a rod-shaped virus which consists of single-stranded RNA and 2130 capsomeres or protein subunits arranged in a hollow right-handed helix.

PSTV (Potato Spindle Tuber Viroid) is an infectious agent of plants which consists of single-stranded closed circular RNA which is not associated with any protein.

Caulimo virus or Cauliflower Mosaic Virus is the first plant virus to be identified with DNA as a genetic material instead of RNA. The virus has the genetic material packed inside the icosahedral head made up of 420 protein subunits.

Thus, only PSTV is not having its genetic material associated with proteins.

So, the correct answer is C.