Mister Rogers is looking rough.

Attenborough’s Life on Earth series from the same era is an absolute classic, if anyone here hasn’t seen it. I give it unironic credit for me being a biologist today.

"Certified"?

By whom?

All of us have the same ancestors that survived those events.

“Next week on Nurse What, the Nurse and his buddy face the Blah-necks!” Voiceover: “ERADICATE!! ERADICATE!!”

Normally, when a break happens, there's another copy of the DNA sequence in the cell - remember you have two copies of each chromosome: one from your mom and one from your dad. So the repair mechanism looks for another similar sequence and copies it (oversimplifying here) to patch the hole.

With CRISPR, if you inject a few thousand or million copies of the altered sequence you want, the odds are very good that the repair system will grab one of those instead of the non-altered sequence on the other chromosome.

When you insert the enzyme and guide RNA, you also add a bunch of copies of short DNA sequences that match the region being cut, but that include the change you want to make. Then when the cell repairs the break, it's likely to grab one of these synthetic sequences to serve as the repair template, and boom. Change made.

"Ooooh, it's so cold. The last thing I want to do is make a nice warm beverage."