And how would I find out the answers (highlighted in blue)? I dont know how than
ID: 91603 • Letter: A
Question
And how would I find out the answers (highlighted in blue)? I dont know how
thank you
1. lac operon and regulation of gene expression You have partially diploid bacterial cells with the following genotype for the lac operon: IT P+ O+ Z+ Y The top row (I P O Zt Yt) refers to one continuous piece of DNA and the bottom row (I P* O Z Y refers to a separate continuous piece of DNA. Fill out the following table with "made" or "not made" for each of the 4 categories (e.g. put made or not made after a. Z gene Y gene Genotype No lactose Lactose No lactose Lactose b. made c. not made d. not made a. not madeExplanation / Answer
Lac operon contains a group of genes present in a single promotor region. The genes present in the lac operon encode for genes that allow bacteria to utilise lactose as an energy source. When lactose is available as the only energy source and glucose is absent, genes present in the lac operon are turned on and produce enzymes necessary for metabolism of lactose.
The three genes of the lac operon are,
lacZ produces -galactosidase which cleaves lactose into glucose and galactose. lacY codes for Beta-galactoside permease, a protein which enables transport of lactose into the cell and lacA codes for the enzyme -galactoside transacetylase. P stands for promotor, I represents regulator gene and O represents operator region.
When, lactose is absent lac repressor binds to the repressor region and enzyme expression in lac operon is blocked. In the presence of lactose, the lac repressor unbinds from the promotor region and the lac operon is turned on. Since, Z gene is responsible for production of -galactosidase, it is made only when lactose is present and is not expressed in its absence. In the given genotype of lac operon, there is a mutation in Y gene. So, it is not expressed irrespective of the presence or absence of lactose. These results correspond to the answers which are highlighted in blue color.