This is the exact Molecular Cell Biology text we were assigned a decade ago (though I’d imagine it’s significantly updated now):
The first principles of a an education in biochemistry are roughly, (1) the central dogma: DNA (transcribed) -> RNA (translated) -> Protein. (2) basic principles of diffusion and chemical equilibria.
Most biochemical systems do work by leveraging potential energy gradients across membranes. For example: there’s a lot of K+ on one side of a membrane, and very little on the other. If you selectively open a channel between the two compartments, we know that statistically the ion (K+) flow will be directionally towards where there’s less K+ (diffusion). Biochemical systems use natural properties of stochastic systems to do work: if we know K+ is traveling in one direction, you can imagine a flywheel of sorts positioned to turn that ion movement into useful energy (ion channels).
The processes by which energy is transferred and utilized is pretty much the field of biochemistry in a nutshell.