Question

1. How were the cell cultures prepared to make it easier for them to absorb the plasmid? What is required to perform this procedure?
2. If the genetically transformed bacteria have acquired the ability to live in the presence of ampicillin, then what can you assume happened with the other genes on the plasmid?
3. Consider your predictions about Plates 3 and 4
4. 1. What factor made the difference in which plate glowed under UV light?
5. 2. Why do you think it would benefit an organism to be able to control the use of genes in response to changes in the environment

Answer 1

The cell culture was treated with Calcium chloride (CaCl2) to make the cells 'competent' to pick up the plasmid.

In the procedure, the CaCl2 treated cells are given heat shock for a brief period (42 degree Celcius for 90 seconds), immediately followed by transferance to ice cold condition, followed by a recovery period of 1 hours so that the cells acclimatize fo normal conditions and to the plasmid.

If the genetically transformed bacteria have acquired the ability to live in presence of ampicillin, then the other genes of the plasmid must also have been taken up by the cells and must be expressing themselves in the cells.

Presence of inducer (that induces expression of GFP from the plasmid in high amount) made the difference in which one plate did not glow under UV light (absence of inducer) and the other plate did (presence of inducer molecule).

If an organism can control its use of genes in response to changes in the environment, then it can

i) gauge environmental conditions and synthesize products accordingly which will help it to survive better

ii) save valuable resources by not producing gene products at a time when they are not needed