You add an unknown phage to a mixture of F⁺ and F− cells of E. coli and plate out the bacteria. The bacterial colonies that grow are all F−. How can you explain this phenomenon?
A) The phage bound to a receptor on the sex pilus, and therefore only infected the F⁺ cells (leaving the F− cells alone).
B) The phage bound to a receptor on the F− cells, leaving only them alive and allowing the F⁺ cells to die off.
C) The phage integrated (lysogenized) the F− cells, giving them a selective advantage over the F⁺ cells.
D) F⁺ cells are uniquely susceptible to phage attack for unknown reasons.
E) F⁺ are well known to die in the presence of any type of bacteriophage.

Question

Quizplus · Accepted Answer

The phage specifically targeted F⁺ cells by binding to a receptor on the sex pilus, which is present only in F⁺ cells, leaving F− cells unaffected.

You Add an Unknown Phage to a Mixture of F⁺