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When lysine becomes available in the environment, LysL can no longer be
When lysine is present in the environment, it is imported into the cell, where it binds
the lysABC operator and blocks the RNA polymerase from binding the operon’s
When lysine is absent from the environment, LysL cannot bind the lysABC operator,
and lysine is synthesized by the cell.
Lysine that becomes available in the environment is imported into the cell, binds to
and changes the conformation of LysL which then falls off the lysABC operator
allowing RNA polymerase to transcribe the operon. Questions #71–74 (4 x 0.25 points)
Some operons lack an operator sequence. Instead these operons have an initiator sequence to
which a regulatory protein binds. Unlike operator sequences, initiator sequences are located on the
“other side” of the promoter. Further RNA polymerase binds to the promoter only if the regulatory
protein first binds to the initiator sequence. The following diagram illustrates this information.
RNA polymerase Regulatory protein RNA polymerase Think about this new information and then answer the following questions by marking (a) for TRUE
and (b) for FALSE on the answer...
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This note was uploaded on 01/21/2014 for the course BIOL 112 taught by Professor Benbasat during the Fall '04 term at The University of British Columbia.
- Fall '04