Within the past fifteen years, the ability of certain bacteria and archaea to provide firewall protection against incoming hostile genetic code (as from viruses or plasmids) has received an amazing amount of research. These bacteria all possess a short sequence of DNA which is entitled CRISPR (clustered regularly interspaced palindromic repeats). Specialized processes attach short snippets of hostile incoming DNA to the CRISPR motif. Once copied into RNA, the CRISPR motif with attached hostile snippet seeks out other incoming hostile sequences (for example from phage viruses). Once such a hostile strand of genetic information has been identified, the CRISPR motif attaches itself to the newcomer and calls on special proteins to destroy the newcomer. The interesting thing is that these destroying compounds come in quite a number of different chemical structures and work in different ways.
Thus a recent article on CRISPR reported: “In the perpetual conflict between bacterial and archaeal hosts and the viruses that infect them, CRISPR-Cas systems [Cas means CRISPR associated system] provide an adaptive defence mechanism through programmed immune memory. These systems show notable variation in the diverse domains and ribonuceloproteins that are involved in these processes. Class I CRISPR systems possess effector complexes that are composed of several Cas proteins whereas class 2 systems rely on single effector, multidomain proteins that mediate crRNA binding and interference. Among known systems, only type III and type VI systems target RNA……..The recently identified CRISPR subtype III-E encompasses a single predicted effector protein that has been computationally characterized as a fusion of four Cas7 group proteins and a putative Cas11-like protein.” [Ahzen Ozcan et al. 2021. Programmable RNA targeting with the single-protein CRISPR effector Cas7-11. Nature 597 #7878: 720-725. See p. 720.]
The article concludes “As the only identified single-protein effector of class I CRISPR systems, Cas 7-11 is distinct from all previously studied RNA-targeting CRISPR effectors, both in domain architecture and functionality.” The fancy effector molecules associated with this firewall system, all destroy incoming hostile genetic code, but the way that they do this is very different among different bacteria and archaea. The spontaneous origin of such fancy molecules is difficult to envisage even once, but multiple times for different designs? Convergence (chance) does not work as an explanation. Intelligent design does work as an explanation!