Question

You are examining the Psf gene and it is known that Psf is normally produced when cells are exposed to high levels of both Ca^2+ and Mg^2+. MetA, MetB, and MetC are important for binding to the promoter of the Psf gene and are involved in regulating its transcription. MetA binds to the A site in the promoter region, MetB binds to the B site, and MetC to the C site. You create binding site mutations in the A,B, and C sites and observe what happens to transcription of the Psf gene. Your results are summarized in a table pictured.

Which transcriptions factors are normally bound to the Psf promoter in the presence of Mg2+ only?
(a) none
(b) MetA only
(c) MetA and MetB
(d) MetA, MetB, and MetC

Answer 1

In the presence of Mg2+ only, the transcription factors that are normally bound to the Psf promoter are MetA, MetB, and MetC.

Step-by-step explanation:

In the presence of Mg2+ only, the transcription factors that are normally bound to the Psf promoter are MetA, MetB, and MetC. This is because MetA binds to the A site, MetB binds to the B site, and MetC binds to the C site in the promoter region. These binding sites are important for regulating the transcription of the Psf gene. Therefore, the answer is (d) MetA, MetB, and MetC.