12. Gene Regulation in Prokaryotes

How would mutations that inactivate each of the following genes affect the determination of the lytic or lysogenic life cycle in mutated λ phage strains? Explain your answers.

cII

Bacterial sRNAs can bind to mRNAs through complementary binding to regulate gene expression. What determines whether the sRNA/mRNA binding will promote or repress mRNA translation?

Why is the CRISPR-Cas system of bacteria considered an adaptive immunity rather than an innate immunity?

How does the molecular mechanism of the CRISPR-Cas system use a viral DNA sequence against that same virus?

In the publication that provided the first evidence of CRISPR-Cas as an adaptive immune system [Barrangou, R., et al. (2007). Science. 315:1709–1712], the authors state that CRISPR-Cas “provides a historical perspective of phage exposure, as well as a predictive tool for phage sensitivity.” Explain how this is true using what you know about the CRISPR locus.