Question

3. Name a procedure which can replace the heat shock process and achieve the same goal: 4. What is the purpose of adding ampicillin to LBA? A. LBA prevents contamination of the plates. B. Ampicillin is a growth factor that stimulates growth of E. coli cells. C. Ampicillin inhibits growth of E. coli cells that do not have amp gene. D. Ampicillin inhibits growth of E. coli cells harboring PBLU plasmid. 5. When B-galactosidase is present, X-Gal turns A. white B. red C. blue D. black

Answer 1

3. Heat shock process is generally used to create temporary pores in the bacterial cell memberane hich allows the passage of the plasmid of interest into the bacteria , to achieve transformation. An alternative procedure that could be used is electroporation, where a high voltage makes the membrane permeable temporarily and facilitates the entry of the plasmid.

4. Ampicillin is added to the media to select between the transformed and non-transformed cells. The plasmids of interest contain an ampicillin resistance gene as a selectable marker. Upon transformation , the bacteria is plated on LBA containing ampicillin. Only the cells which are transformed and contain the plasmid hich contains the ampR gene will be able to survive, while ampicillin will inhibit the growth of cells which do not contain the plasmid and ampR gene. Therefore ,option C is correct.

5. X gal is a substrate for beta - galactosidase. In the presence of beta - galactosidase X gal is cleaved into galactose and an indole compound that dimerises to give blue colour.(5,5 dibromo 4,4 dichloro indigo)