Question

(a) Why must a cell be made 'competent' in bio-technology experiments? How does calcium ion help in doing so?

(b) State the role of 'biolistic gun' in biotechnology experiments. [3]

Answer 1

(a) DNA being a hydrophilic molecule, cannot pass through cell membranes, hence the cells should be made competent to accept the DNA molecules ,as competency is the ability of a cell to take up foreign DNA. [1]

Calcium ion helps in increasing the pore size in cell wall which enables the cell to take up the recombinant DNA. Both the plasma membrane and the DNA is negatively charged, the positive calcium ions form a bridge between them and bring them closer. [1]

(b) To introduce foreign DNA into host plant cells, they are bombarded with high velocity gold or tungsten coated micro-particles with DNA molecules. This is known as biolistic or gene gun. [1]