We've seen this movie...

 Scientists have inserted human genes into yeast. Ack! Yeast monster!

Actually, yeast cells operate remarkably like human cells, which is probably part of why food fermented with yeast is so important to us.

In this case, it's human muscle genes.

This is something that's being worked on, and it allows us to analyze a single process. The most recent one involves a mechanism that is involved in some cancers, so we could use it to study tumor processes safely.

But I can't help but think of the sourdough starter familiar from Kingfisher's A Wizard's Guide to Defensive Baking.