Question

Kappa particles were discovered by-
(a)Correns
(b)Sonneborn
(c)Rhoades
(d) Bycott et al.

Answer 1

Hint: In 1938, he reported that some strains or genetic determinants contain kappa particles located in the cytoplasm and are known as “Killers “ or killer traits. he referred to these cytoplasmic genes as “plasma genes”

Complete answer:
Kappa particles were discovered by Sonneborn. He reported that a gram-negative symbiotic bacterium called Kappa Particle was found in the cytoplasm of certain strains of the protozoan named Paramecium aurelia. Kappa particles contain DNA and protein and are about 2 μ x in diameter.

Additional Information: -Kappa particle is a self-replicating unit. Paramecium aurelia has 2 types of strain, Sensitive, and Killer strain.
-Individuals which are not possessing Kappa particles are sensitive and they are killed by a poison ‘paramecin’ which is secreted by Killer individuals.
-The kappa bearers, called killers, are immune to the poison that they ultimately unleash.
-The secretion paramecin is harmless to the killers. The different killer strains are having different means of killing their victims.
-Most of them do not kill their mates. But there are some strains that instead of killing from a distance by secretion, kill their mates through close contact.
-The killer character has a nuclear as well as the cytoplasmic basis.
-Mr. Correns was a German botanist and geneticist, who is known for his independent discovery of the principles of heredity,
-Rhoades discovered male sterility.

So, the correct answer is,’ Sonneborn’.

Note: -They are actual killers only when their cytoplasms contain kappa particles which in turn produce the lethal poison.
-Paramecium generally reproduces by conjugation method, a system of parasexual reproduction, and autogamy the conjugation is accomplished in a short duration normally no exchange of cytoplasm takes place between the killers and sensitive individuals.