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Unformatted text preview: Biological Sciences 101 Name_________________________ Dr. Mark Sanders Summer Session II 2011 Last four digits of ID ____________ Pop Quiz 2A 1. Fill in the table for the following partial diploids using + to indicate production of functional -galactosidase (-gal) or permease (perm) and - to indicate no production of functional enzyme. (8 pts) Induced Not induced -gal Perm -gal Perm a. I + P + O C Z- Y + /I- P + O + Z + Y- + +- + b. I + P + O + Z + Y- /I S P + O + Z + Y----- 2. What does lac I produce and how does this product function in regulating transcription of lac operon genes? (4 pts) The lac I gene produces the repressor protein. In the noninduced state, the repressor protein uses its DNA-binding domain to bind lac O and block operon gene transcription. In the induced state, lactose binds the allosteric domain of the repressor, shifting the conformation of the protein and preventing its binding to lac O . Without repressor bound to the operator, transcription of the operon genes can take place. Biological Sciences 101...
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- Summer '08