Practice Problem 78 You are investigating a new bacterial operon that contains f

Question

Practice Problem 78

You are investigating a new bacterial operon that contains five regions (A, B, C, D and E) involved in coordinated regulation of transcription. One is the gene for a regulatory protein, one is the binding site for the regulatory protein, two produce structural enzymes (enzyme 1 and enzyme 2), and one is the promoter for the two enzyme genes.

The table below shows data collected for five different bacterial strains. A "+" indicates that the structural enzyme is produced and a "-" indicates that the enzyme is not produced. The "signal" is a molecule that either represses or induces the operon. Use the information to determine how the operon is regulated, and the identity of each region.

Part A

In the wild-type operon (A+ B+ C+ D+ E+), how does the presence of the signal affect expression of the structural enzymes ?

In the wild-type operon (A+ B+ C+ D+ E+), how does the presence of the signal affect expression of the structural enzymes ?

Strain Enzyme 1 Enzyme 1 Enzyme 2 Enzyme 2 -signal +signal -signal +signal A+B+C+D+E+ + - + - A-B+C+D+E+ - - - - A+B-C+D+E+ + + + + A+B+C-D+E+ + - - - A+B+C+D-E+ + + + + A+B+C+D+E- - - + -

Explanation / Answer

Third one is the Answer. That is The presence of the signal stops the production of the structural enzymes. Without the signal the structural enzymes are produced.

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