73.
Besides a high voltage shock, what is another method to make E. coli competent to take up “naked” DNA?
A:
High concentrations of calcium ions followed by high temperature
B:
High concentrations of calcium ions and several hours on ice
C:
Large amounts of DNA added directly to a bacterial culture growing at 37 °C
D:
High concentrations of minerals followed by high temperature
The answer is:
A