I love these discoveries. Are proteins easy to detect and isolate? How does one tell where a protein begins and ends and if one megs protein is not just a bunch

I love these discoveries. Are proteins easy to detect and isolate? How does one tell where a protein begins and ends and if one megs protein is not just a bunch of smaller proteins. Also how do they discover the functions of proteins? Just turn them off and on and try to see what effect it has on the body? This is such a super interesting field; Any one have good resources (youtube) that show how this stuff is done in the lab?