Beta-Galactosidase and Western Blot

Essay by tjavanUniversity, Bachelor'sB+, September 2013

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Beta-Galactosidase and Western Blot 0

1. EMG 9 and EMG 26 contain strain lac-(I- Z+ Y+) and strain lac - (I+ Z- Y-)respectively.Three genes huddled together on the chromosome are required for two strains of E.coli to utilize lactose.Consisting of three genes, namely, lacZ, lacY and lacA, the lac operon orderly handles these genes to code specific enzymes necessary for the metabolism of lactose. The genes lacZ, lacY and lacI would code for beta-galactosidase, galactosidase permease and lac repressor respectively. Regulation of lac operon is also tight and the operon's negative control is made possible by lac repressor (Hill, 1996). With the presence of lac repressor, lac operon will be deactivated and will remain on this state unless acted upon by lactose. Consequently, transcribing the genes inside lac operon will be prevented. Lac operon only operates with the presence of lactose and absence of glucose.

However, when both lactose and glucose are available, the latter is primarily preferred over metabolism. Lactose will only be cleaved into glucose and galactose with the aid of beta- galactosidase and its transportation inside the cells will be facilitated by galactoside permease (Hayes et al., 2010).

Inside EMG26, mutation can be noted on lacZ gene. Production of beta-galactosidase will also not occur regardless of the current state of lac operon, whether it is activated or not; or whether lactose is present or absent (Snyder, et al., 2007). Moreover, binding of lac repressor to its operator is also apparent which in turn prevents the transcription of lac genes through the inhibition of RNA polymerase. However, this inhibition may be counteracted with the presence of allolactase, an alternative lactose formation generated from rearrangements of beta-galactosidase. When allolactase binds, alteration in the conformation of repressor will occur in such way that it...