How much harder would it be to simulate various human brain cells?
Mycoplasma genitalium has less than 600 genes. We have something like 30,000. So a ballpark answer might be "at least 50 times harder". I expect it would be very much more than that, as a free-living microbe has much simpler interactions with everything around it, while a neuron can have connections to thousands of other neurons. Neurons are also much bigger, with more physically complex stuff.
Thinking in terms of uploads, it might not be necessary to simulate all that in order to duplicate whatever is important about its function. If you don't k...
"A Whole-Cell Computational Model Predicts Phenotype from Genotype" by Jonathan Karr et al.
This paper appeared a few days ago in Cell, and describes a computational simulation of the bacterium Mycoplasma genitalium, conducted at this lab. The paper is behind a paywall, but is blogged about here. The simulation software is freely available from the project web site.
From the abstract: "Here, we present a ‘‘whole-cell’’ model of the bacterium Mycoplasma genitalium, a human urogenital parasite whose genome contains 525 genes. Our model attempts to: (1) describe the life cycle of a single cell from the level of individual molecules and their interactions; (2) account for the specific function of every annotated gene product; and (3) accurately predict a wide range of observable cellular behaviors."
According to an editorial commentary in the same issue, this is the first simulation of a complete free-living microbe.