system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes CRISPR a *synthetic* biology innovation?

I'm hoping to understand the nature of synthetic biology, as a lot of the explanations I've received assume a lot of internal knowledge.
gpt
Previously, we have believed that cellular DNA is like words chiseled into a stone tablet—what is written there is constant and unchangeable.  The discovery of the CRISPR system has challenged this belief.  DNA in some species now is more like an internet server.  Viruses come in and try to hack the server to change its programming.  The CAS protein is like a firewall that recognizes someone attempting to infiltrate the system.  CRISPR is where the firewall stores its blacklisted IP addresses.  CAS adds the IP address of the invading hacker into the web host to prevent the viruses from editing the server.  Now that scientists know that this blacklist exists, we can add all kinds of things to the blacklist that aren’t IP addresses.  We can access the part of the server that’s meant to be changed and make the blacklist (CRISPR region of the genome) store our information.  The full use of CRISPR has not yet been realized, but the fact that we can insert specific genes into living cells is a huge breakthrough.  The synthetic part comes in with us adding that information where it doesn't belong.