[Campbell Biology P.425] Based on the provided data and graph, which of the following statem... | Practice Question

Based on the provided data and graph, which of the following statements correctly describes the effect of deleting a control element and its inferred normal role?

  • A: Deletion of control element 1 leads to a reduction in reporter gene expression, indicating it normally functions as an activator.
  • B: Deletion of control element 2 leads to an increase in reporter gene expression, indicating it normally functions as an activator.
  • C: Deletion of control element 3 leads to a reduction in reporter gene expression, indicating it normally functions as a repressor.
  • D: Deletion of control element 2 leads to a reduction in reporter gene expression, indicating it normally functions as a repressor.

Explanation

The bar graph shows that deleting control element 1 results in reporter gene expression dropping to approximately 20-30% of the control level. This reduction indicates that element 1 normally promotes activates gene expression. If an activator is removed, expression decreases. Conversely, deleting elements 2 and 3 causes an increase in expression to about 140-150% , suggesting they normally repress gene expression. If a repressor is removed, expression increases.