Need help explaining 2,3 and 4 PART 2: REGULATING EXPRESSION WITH ACTIVATORS AND

Question

Need help explaining 2,3 and 4 PART 2: REGULATING EXPRESSION WITH ACTIVATORS AND REPRESSORS, A CASE STUDY During your summer months, to escape the heat of Davis, you work with a group of scien- tists at the North Pole to study the bacterium E. luminescent. This is a bacterium that lives in dark icy waters. Your colleagues have found that during certain times of the year, large populations of E. luminescent glow. While you were away at school, your colleagues identi- fied a signal peptide that when introduced to a population of E. Luminescent in the lab, will cause the bacterium to start glowing. Here are the notes they have written for you to bring you up to speed. The signal peptide is produced by E. Luminescent. The signal peptide can then exit the cell and enter a neighboring E. Luminescent. Thus, overtime, an entire population of E. Lumines- cent will come into contact with the signal peptide. Upon contact with the signal peptide, the bacteria produce a luminescent protein Glow Bright (GB). The production of GB can be up- regulated by self-production of the signal peptide Peptide Gene Cirouit high Fipure Legend Signal Transcription Peptide Factors mRNA encoding the signal molecule Signal Molecule Coding Region Site Promoter mRNA encoding the GB protein Glow Bright Protein RNA Polymerase Regulatory Glow Bright (G) Coding Region Site 101

Explanation / Answer

1. In the presence of the signal peptide, the transcription of GB and signal peptide is promoted. The signal peptide binds to the repressor and relieves RNA polymerase from repression so that GB is transcribed. GB protein binds to the activator and recruits RNA pol to the promoter of signal peptide gene.
2. In the absence of signal peptide, the transcription of GB and signal peptide is inhibited. The repressor binds to the operator of GB gene and inhibits the function of RNA Pol. If GB is absent, activator-mediated recruitment of RNA pol to the signal peptide locus is also eliminated.
3. If the repressor could not bind to DNA, the expression of GB and signal peptide would be constitutive irrespective of the presence or absence of the signal peptide.
4. If the activator could not bind to GB, transcription of signal peptide does not occur. This will also result in the decreased expression of Gb from its genomic locus.

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.