Question

In case of mixing his+ leu- strain with his- leu+ strain we can see that the auxotroph behaves as prototroph for these two genes. This is because of________________

(a) One is synthesizing one amino acid and giving it to the other type

(b) They fuse to form similar diploid bacteria

(c) Both will have the same genetic composition at the end

(d) They share the RNA by extracellular processes

The question was asked during an interview.

I'd like to ask this question from Gene Mapping in Bacteria by Conjugation topic in chapter Genomics : The Mapping and Sequencing of Genomes of Cytogenetics

Answer 1

Right choice is (c) Both will have the same genetic composition at the end

Easy explanation: Genetic transfer, mainly by conjugation will result in incorporation of the His+ Leu+ gene in both the strains at the end. Then they can produce both these amino acids by themselves and grow on minimal media. This is not by extracellular process but by contact.