Phage Lab

1606 words 7 pages
Alisha Patel
Genetics Lab
TA: Vasant Chary
March 21, 2012

Phage Titering of a Bacterial Culture and Recombination of Bacteriophage


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
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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


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