There are a lot of chemical reaction that happen in our cells. I wonder how they discovered how they work? Seems to me that would be very difficult.
For example chem A + chem B leads to Chem C. Or Chem D bonds to some point on a cell.
For a real example, cells need insulin to use sugar. That was discovered in 1920s.
I guess this is why people win Nobel prizes because this stuff is very difficult to figure out. (The guys who found insulin won a Nobel)
I’m not really sure what your question is, but this might be a good starting point to learn more about the history of biochemistry.
One technique that’s used is isotope tagging. You start by producing a molecule that the organism uses, but replace all of the atoms of one element with an uncommon (but safe) isotope of that element. Then, you feed that substance to the organism, let nature take its course, and see what new chemicals those rare isotopes end up in.
Broadly speaking, there are several other sorts of “reductionist” approaches. For one, you can isolate any sort of chemical, protein, or enzyme (a protein that catalyzes a reaction) from a cell, given enough starting material and [del]peons[/del] grad students. Second, you study mutations in an organism that alter the biochemistry in interesting ways. Third, starting in the 70s or so you can directly manipulate the DNA that produces proteins including enzymes.
So, for a very broad example, you can use isotope labeling to first find that A + B react to form C. Then, you can put purified A and B in a test tube with different proteins in the cell until you find that Enzyme X that catalyzes the A + B -> C reaction. Later on you mutate the gene for Enzyme X to see how that changes the whole cascade of reactions involving A, B, and C.
lots of chemistry that happens in an organism can happen in a test tube.
if someone has a thought on what a chemical reaction might be then it can be tried outside to see if similar results occur. the chemicals or some of them might have to be extracted and purified from cells.
there is no single answer. it depends on the when the science was done and what methods were available at the time. people have made hypothesis about biochemistry yet it might be years or decades before it can be proven due to what methods were available at the time.
biology and chemistry are very diverse. it is truly amazing at how things get done.
Yeah. What you’re really asking here is “how does the field of biochemistry do stuff?” which is, as you might imagine, a question that would take several large textbooks to answer.