A repressor protein would have which of the following effects on repressible genes with a negative control mechanism?

A) stimulate transcription in the presence of a corepressor
B) turn off transcription in the presence of an inducer
C) stimulate transcription in the presence of a coactivator
D) turn off transcription in the presence of a corepressor
E) does not participate in negative control mechanisms

Repressor Protein

A negative regulatory protein that inhibits transcription when bound to DNA; some repressors require a corepressor to be active; some other repressors become inactive when bound to an inducer molecule. Compare with activator protein.

Repressible Genes

Genes whose expression is decreased or halted by the presence of a specific substance, often the end product of the gene's pathway.

Negative Control

An experiment or trial that does not include the factor being tested and is used to ensure that the experiment works by way of comparison.