Just to chime in here, for science passages with a ton of unfamiliar acronyms, one thing that can be helpful is to highlight what's *familiar* to you instead of highlighting every *unfamiliar* gene name, etc. This is because MCAT questions tend to be written about content that you know from your MCAT studying, not about random new things. Of course, it's possible that questions will ask about new genes in a completely passage-based way, but that's relatively rare. It's way more common for them to be using all of these acronyms to try to intimidate you and then ask about content that you *do* understand.
For example, if you see a passage that's full of terms like "caspase-3" and "MAPK-ERK pathway," highlighting those terms won't be very helpful, because (at least from your MCAT studying alone) you don't know anything about them. But if they mention that one of these enzymes or pathways *phosphorylates* something, highlight "phosphorylates," because we *are* familiar with that, and they could easily ask about it (for example, in the context of which amino acid on another protein might be likely to be phosphorylated).
Similarly, a lot of long unfamiliar enzyme names contain familiar parts, even if we have no clue what the enzyme does overall. For example, take something like [histone H3]-lysine(4) N-trimethyltransferase. A passage full of terms like this would be super intimidating, but in reality we're already familiar with histones, lysine, and (maybe) the general function of a transferase, which lets us infer more than enough about this enzyme's function. Again, I wouldn't recommend highlighting the whole thing, but you could definitely highlight "histone" and "lysine" (the MCAT takes practically every opportunity to ask about amino acids, so seeing an amino acid in a protein name is a great warning sign).
Good luck