Alisha Patel
Genetics Lab
TA: Vasant Chary
March 21, 2012

Phage Titering of a Bacterial Culture and Recombination of Bacteriophage

OBJECTIVES:

The main objectives of this experiment included making dilutions of solutions, plating phage or bacteria, and determining the number of bacterial viruses or phage in a suspension. It was also conducted to demonstrate that two different mutants of phage T4 can exchange genetic material to give rise to wild-type phage. The experiment was used to distinguish mutants from wild-type by their host specificity. The recombination in bacteriophage was performed to determine the concentration of unadsorbed phage from the U series plates, total concentration from B series, and concentration of …show more content…

Mutant strains could only be formed on E. Coli B whereas wild-type phage was able to grow on both E. Coli K and E. Coli B. Both mutations are part of the same cistron in the rII regions.
E. Coli B is infected multiple times with both mutants. Phenotypically, the appearance of plaques on E. Coli B in the parents for both phages was large whereas there were no plaques on E. Coli K. The recombinants for double mutant were large while the wild-type was small in E. Coli B whereas in E. Coli K, there was no plaque for double recombinants and small plaques in the wild-type. The genotypes went accordingly.
The parents genotype would look like: 31 ---------X----------------------------------- 29 ----------------------------------X----------
The recombinants would look like: double mutant ---------X-----------------------X---------- Wild-type ----------------------------------------------
It is important to note the difference between recombination frequency and reversion frequency. Recombination frequency was found by dividing the titer on K by the difference between the titer on B and the titer on U and multiplying by 2. The titer on K