(a) Why must a cell be made 'competent' in biotechnology experiments ? How does calcium ion
help in doing so ?
(b) State the role of 'biolistic gun' in biotechnology experiments. (3 marks)
(a) (i) To take up the hydrophilic DNA from the external medium. DNA is a hydrophilic molecule, it
cannot pass through plasma membranes. In order to force bacteria to take up the plasmid,
the bacterial cells must be made competent to take up DNA.
(ii) Divalent calcium ions increase the efficiency of DNA entering the cell through pores in the
(b) Role of 'biolistic gun'. To introduce alien DNA into the plant cells by bombarding them with high
velocity micro particles (gold or tungsten coated with DNA).