Decide whether each of these statements is true or false and justify your answer.

- The leader sequence composed of 162 nucleotides in the tryptophan operon

- Riboswitches can regulate metabolites, whose synthesis or activity is controlled by the genes encoded by the mRNA.

- Riboswitches can be found in archaea, fungi, and plants and may prove to be present in animals as well.

- Riboswitches can recognize a broad range of ligands

- In Bacillus subtilis, for example, approximately 10 percent of this bacterium’s genes are regulated by riboswitches.

- CRISPR loci serve as a “molecular memory” of previous viral attacks