Fluctuation test

Fluctuation test- (by Luria and Delbruck) Distinguish between adaptive and spontaneous mutation.

• It is a test to determine the randomness of mutation in a bacteria.

• When bacteriophage T1 infects wild type E.Coli, it binds to a receptor named TonB in the outer membrane of the bacteria.

•  Most of the bacteria are killed  by the insertion of phage  and new phages are released after replication .

• When phage infects mutant type due to mutation in TonB gene altered receptor to which T1 can no longer bind and the cells are survive .

•  Luria and Delbruck measured the number of mutants resistant to phage T1 in a large number of replicate cultures of E.coli. The numbers depend on how early during the growth period the first mutant cells arose.Early generation mutations give more mutant cells than late mutation.
• The test is called fluctuation test as it measures the amount of fluctuation in the number of mutants found in replicate cultures.

                                            Image source -http://slideplayer.com/slide/2816451/

Thank you for visiting my blog.Please feel free to share your comment on this article ,Please subscribe and share the articles to get more such articles.