Question

QUESTION 7 Imagine you discovered a strain of E. coli lacking a gene necessary to synthesize the amino acid histidine (they are therefore his). You attempt to rescue the cells by transforming them DNA from a wild-type his "donor" strain, and you plate your transformed sample and all controls on plates lacking histidine (-His) as well as plates containing histidine (+His). Shown below are the results of your transformation. + indicates there was growth, and - indicates there was no growth. What can you reasonably conclude from these results? Sample Plate -His +His 1 + + + Recipient his cells Donor his cells DNA only Transformed Recipient cells 1 + + + The DNA was contaminated with Recipient cells, but this doesn't affect the conclusion that the transformation was successful. The Recipient cells were contaminated with Donor cells, so the apparent success of the transformation is inconclusive. The DNA was contaminated with Donor cells, making it impossible to conclude whether or not the transformation was successful. This experiment was successful and there was no contamination.