Question

T.O. Diener discovered a
(a) Bacteriophage
(b) Free infectious RNA
(c) Free infectious DNA
(d) Infectious protein

Answer 1

 
Hint: T.O. Diener, a plant pathologist, discovered that the disease- causing microorganism in potatoes was a subviral agent that lacks one of the essential components to be a virus known as viroid.

Complete Step by Step Answer: Theodor Otto Diener was a Swiss- American Plant pathologist who discovered small self- replicating particles which lacked protein coats and had infectious free RNA particles. He named these microorganisms as Viroid which meant L. virus- poison, eidos- diminutive. The molecular weight of viroids is very low, lower than the virus. These are the smallest causative agents known till now. Viroid replicates in the nucleus of the chloroplast through RNA replication mechanisms which are done in the presence of enzyme RNA polymerase II, which it takes from the host cell which uses it to synthesis mRNA from DNA. So, the correct answer is, “Free infectious RNA.”

Note: - Viroid is an obligate parasite and requires a host to survive.

- These viroids are known to cause disease in plants only like, potato spindle tuber disease, Chrysanthemum stunt, and Citrus exocortis. - The RNA is tightly folded to form circular or linear structures in viroids. - Although viroids have nucleic acid, they do not code for proteins. - Virions, prions, viruses, virusoids, and viroids all are different entities. - A virus is a microorganism that contains RNA or DNA as a genetic material with a protein capsule. - A virion is a completely functional virus that can infect the living tissues. - A virusoid is an RNA containing microorganism that requires a virus- infected cell to replicate itself. It can not replicate without the help of a virus. - A prion is a misfolded protein that affects normal protein to misfold and thus causes diseases.