You are working in a lab that studies tobacco mosaic virus (TMV). You wish to perform follow up experiments to the Fraenkel-Conrat/Singer experiments. You use the Holmes ribgrass (HR) strain of TMV that they used, which produces streaks along the veins and contains histidine and methionine in the TMV capsid protein. You also use a second TMV strain that you've isolated, called Purp, that causes purple lesions on the leaves, and lacks histidine and methionine in the TMV capsid protein. If you use Purp RNA and HR proteins to create reconstituted viruses, what lesions do you expect will form, and what will the amino acid composition of the capsid protein be?
A) Purple lesions, histidine and methionine in the capsid protein
B) Purple lesions, no histidine and methionine in the capsid protein
C) Streaks on the veins, no histidine and methionine in the capsid protein
D) Streaks on the veins, histidine and methionine in the capsid protein

Question

Quizplus · Accepted Answer

Since the Purp strain lacks histidine and methionine in the capsid protein, creating reconstituted viruses using HR proteins would result in a capsid protein without those amino acids. Additionally, the Purp strain causes purple lesions on the leaves, so the resulting reconstituted virus would also cause purple lesions rather than streaks along the veins. Therefore, the answer is B: Purple lesions, no histidine and methionine in the capsid protein.

You Are Working in a Lab That Studies Tobacco Mosaic