12. Gene Regulation in Prokaryotes

Tryptophan regulates the trp operon by doing what?

Attenuation uses what molecule to regulate the trp operon?

What is the name of the sequence responsible for regulating the trp operon through attenuation?

If tryptophan levels are low, attenuation does what to the trp operon?

How do we know that the trp operon is a repressible control system, in contrast to the lac operon, which is an inducible control system?

Transcriptional regulation of operon gene expression involves the interaction of molecules with one another and of regulatory molecules with segments of DNA. In this context, define and give an example of each of the following:

Attenuation

Transcriptional regulation of operon gene expression involves the interaction of molecules with one another and of regulatory molecules with segments of DNA. In this context, define and give an example of each of the following:

Corepressor

Identify similarities and differences between an inducible operon and a repressible operon in terms of

The presence and action of allosteric regulatory molecules.

Identify similarities and differences between an inducible operon and a repressible operon in terms of

The organization of structural genes of the operon.

Is attenuation the product of an allosteric effect? Is attenuation the result of a transcriptional or a translational activity? Explain your answers.

The trpL region contains four repeated DNA sequences that lead to the formation of stem-loop structures in mRNA. What are these stem-loop structures, and how do they affect transcription of the structural genes of the trp operon?

Explain the circumstances under which attenuation of operon gene expression is advantageous to a bacterial organism. Would you expect attenuation to be found in a single-celled eukaryote? In a multicelled eukaryote?