Hello, long time no speak

Let me start by saying I'm not sure how exactly to formulate the question I'm trying to ask...
My question concerns how consciousness/sentience is a property of matter.
At what level is matter self-aware? Is it a proper of quarks, protons/neutrons and/or electrons?
A brain, in the materialistic view, is nothing more than a complex arrangement of molecules which in turn are composed of atoms, electrons, protons/neutrons etc. Is the brain essentially an organic computer? If so, who/what programs the computer?
How is choice possible? It's clear (to me) that we all have the ability to make choices. Computers can only act according to pre-programmed instructions. We humans are capable of making decisions in unforeseen situations. Why doesn't our brain "crash" in these situations?
Is it possible for matter to be self-aware?
Thoughts welcome.
Thanks,
Noel.