1.7 Cracking the Code

summary

Microbes, like plants and animals, are subjected to constant assault by viruses.
Bacterial viruses, or bacteriophages, outnumber their host cells ~10-to-1, and are a major driver of genome evolution and immune system diversification.
Bacteria possess both innate and and adaptive immune systems.
CRISPR-Cas systems use guide RNAs to target matching viral sequences for degradation.
CRISPR-Cas systems are highly diverse and rely on a multitude of RNA and protein molecules for distinct immunity pathways.
Many mobile genetic elements, including viruses and transposons (aka jumping genes) have hijacked CRISPR-Cas to undergo RNA-guided DNA insertion.