What is "essential" in a genome? A good article, with links to primary sources. A complicated question even before you step out of the lab and into varying real life conditions. quantamagazine.org/how-many-genes…
Yeast are also an interesting model organism for this because yeast tend to lose genes that they don't need. So, while we have an "essential" (without it they die) map, the "the yeast thinks its important" map is the whole genome.
Figuring out why, and how the "less important" genes link into the larger network for possibly outsized effects when paired with others could be very enlightening to understanding more complex eukaryotic systems.
