Question

The correct sequence of making a cell competent is
A. Treatment with divalent cations incubation of cells with recombinant DNA on ice heat shock (42℃ ) placed on ice.
B. Heat shock (42℃ ) incubation of cells with recombinant DNA on ice treatment with divalent cations placing on ice.
C. Treatment with divalent cations placed on ice incubation of cells with recombinant DNA on ice heat shock(42℃ ).
D. Incubation of cells with recombinant DNA on ice heat shock (42℃) treatment with divalent cations placing on ice.

Answer 1

Hint: For taking up the plasmid the cell is made competent. This is done by using divalent ions usually calcium ions and also by using various techniques.

Step by step answer:Competent cells are the cells which are able to use bacterial cells that possess altered cell walls by which foreign/recombinant DNA. Most of the cells cannot take up DNA without chemical or electrical treatment. The standard method for making the bacteria permeable to DNA involves treatment with divalent ions usually calcium ions. The DNA molecule enters into the bacteria through the pores in its cell wall after treating with calcium divalent ions. Recombinant DNA is then forced into such cells by incubating the cells with recombinant DNA on ice followed by placing them at heat shock and then again into ice. This makes the bacteria to take the recombinant DNA
Hence, the correct answer is option A.
Treatment with divalent cations incubation of cells with recombinant DNA on ice heat shock (42℃ ) placed on ice.
Additional information:
Competence is distinguished into natural competence and artificial competence and transformation
There are two main methods for the preparation of cells by artificial competence are the calcium chloride method and electroporation.

Note: Recombination of DNA takes place first in the bacteria. Different techniques are used for making a cell competent for both plant and animal cells. For example, the gene-gun method, heat shock, micro-injection, electroporation, etc.