Question

Cells are made competent to accept foreign DNA by
i. Transferring the cells to calcium rich environment
ii. Electrolysis
iii. Adding restriction enzymes
iv. Electroporation

• A. ii and iii
• B. iii
• C. i
• D. i and iv

Answer 1

The correct option is D i and iv

DNA and cell membrane both possess a negative charge, this creates repulsion between the two during transformation. To overcome this, cells are treated with bivalent cations like $C{a}^{2+}$ which render a positive charge to the membrane. This is followed by a quick heat shock which allows DNA to pass into the cell. Electroporation method involves the application of high voltage of about 1,000 to 10,000 volts across bacterial cells per cm for a few milliseconds. This takes place in a specialized device called an electroporator. This allows pore formation on the cell membrane allowing DNA to pass into the cell.