Which of the following statements is not true of the cI (lambda repressor) protein in bacteriophage lambda?

-can repress transcription if the cI gene

-capable of both positive and negative auto regulation

-can repress transcription of the cro gene

-can activate transcription of the cro gene

-can activate transcription of the cI gene

Among the following statement about the lambda bacteriophage the one that is not true is that capable of both positive and negative auto regulation

Answer: Option A

Explanation:

The lambda bacteriophage is a virus that affects the bacteria especially the Esrechia coli bacterium, the genetic material gets injected to the cytoplasm of the bacteria from its head leaving back the protein capsid of the cell, ones it gets into the host cell it either follows the lytic or the lysogenic cycle. In the lytic cycle it replicates inside and causes rupture of the host whereas in a lysogenic phase it coexists with the host.

The correct answer is - can activate transcription of the cro gene.

This is because in the presence of Ci only the cI gene may be transcribed (CRO gene cannot).

Only in the absence of cI proteins, the cro gene may be transcribed. Both genes are repressed at high concentration of Ci.