Question

You set up a transformation hoping that a strain of E. coli will take up a plasmid containing an ampicillin resistance gene, making the strain able to grow on LB + amp. To see if the transformation worked, you set up four plates: (1) Untransformed E. coli cells on LB plate (2) Untransformed E. coli cells on LB + amp plate (3) Transformed E. coli cells on LB plate (4) Transformed E. coli cells on LB + amp plate. Your find that after 1-2 days, (1) grows, but (2), (3), and (4) do not. Explain these results: can you tell if the transformation was successful? Why or why not?

Answer 1

Let me first explain you the points from 1 to 4

1) The untransformed E.coli cells are the normal cells that have the normal ability to grow in LB plate with no ampicillin ,thats why growth was observed.

2) Untransformed E.coli cells are the cells with no ampicillin resistance gene, hence when they are set up in LB + amp plate they didn't grow.

3) and 4) Normally tranformed cells grow in both LB and LB + amp plate, but in these two cases due to toxicity of the gene (in case on point 3) and toxicity of gene & antibiotic ( in case of point 4) the cells didn't grow.

Hence from the above explanations we can tell that the transformation wasn't successful because the transformed E.coli didn't show any growth on which the whole experiment was based.