Question

DNA from a strain of E. coli with the genotype met+arg+ is used to transform a recipient strain with the genotype met-arg-. The following numbers of transformed cells were recovered.

met+, arg+ 312
met+ arg- 821
What is frequency of cotransformation?

Answer 1

The frequency of cotransformation in an E. coli transformation experiment is calculated by dividing the number of cells that acquired both genes by the total number of transformants. The given data shows 312 met+ arg+ transformants and 821 met+ arg- transformants.

Step-by-step explanation:

The student has asked about the frequency of cotransformation after performing an experiment on E. coli using DNA transformation to introduce two genes (met+ and arg+) into a recipient strain that lacks these genes (met- arg-). The frequencies of each transformed cell type were given for those that took up both genes (met+ arg+) and for those that took up only the met+ gene (met+ arg-).

To calculate the frequency of cotransformation, one needs to take the number of cells that received both genes and divide it by the total number of transformants (both types). So, in this case, the calculation would be 312 (the number of met+ arg+ cells) divided by 312 + 821 (the total number of transformants), which gives the cotransformation frequency.