Arrange the following steps for making the bacterial cell competent to take up DNA, in chronological order. I. Incubation of cells with recombinant DNA on ice. II. Incubation of cells with recombinant DNA at 42 degree Celsius. III. Treating cells with a specific concentration of a divalent cation such as calcium.

Question

Arrange the following steps for making the bacterial cell competent to take up DNA, in chronological order. I. Incubation of cells with recombinant DNA on ice. II. Incubation of cells with recombinant DNA at 42 degree Celsius. III. Treating cells with a specific concentration of a divalent cation such as calcium. (A) III followed by II followed by I followed by II (B) III followed by I followed by II followed by I (C) I followed by II followed by III followed by II (D) II followed by I followed by III followed by I

Tardigrade Admin · Accepted Answer

rDNA technology is a process to develop transformants. Transformants are bacterial cells which have successfully accepted the DNA sequence of our choice. To enable the process the cells are made competent to take in the desired DNA sequence as the DNA cannot pass through the cell membrane directly. The cells are first treated with calcium cation to increase the efficiency of DNA uptake. The cells are then kept on ice with the recombinant DNA followed by heat treatment at 42 degree Celsius for short period and again on ice. This treatment helps the bacterial cell to take in the rDNA sequence easily.