Two Bacterial Genes Are Transduced Simultaneously

question 21

Multiple Choice

Two bacterial genes are transduced simultaneously. What does this suggest about their proximity to each other within the original host genome?

• A) Nothing. It's highly likely that two separate virus particles were carrying each gene, and that they coinfected the new target cell at the same time. This could mean the two original genes might not even be from the same original host cell!
• B) It's highly likely that the two genes are located next to each other in the host cell chromosome. Since transduction results from a packaging error or an excision error that occurs during the infection cycle of the bacteriophage, the genes must lie close to each other to be transduced into a new cell simultaneously.
• C) They must be within five gene lengths of each other, but not necessarily immediately adjacent. If they were immediately adjacent, the transposons that facilitate the transfer of genetic information between the two cells wouldn't be able to "jump" into them.
• D) It doesn't mean anything. Transduction relies on the ability of a cell to take up foreign DNA. It's possible here that the cell has simply taken up two separate bits of DNA at the same time from the surrounding environment.
• E) It's highly likely that one gene was on the chromosome but the other was actually on a plasmid; if those two elements are in one cell, genes can be transferred simultaneously.