In fact, cysteines are the only amino acids capable of forming covalent bonds, which they do with their particular side chains. Because of side chain interactions, the sequence and location of amino acids in a particular protein guides where the bends and folds occur in that protein (Figure 1).
gas exchange between the pulmonary blood and lungs where oxygen from fresh air in lungs moves into the blood and excess CO2 from the blood moves into the lungs.xygen and carbon dioxide that are transported to and from the lungs and tissue cells where oxygen is pumped throughout the body is CO2 is pumped back into the lungs.
Gas Exchange in the Lungs. Gas exchange in the lungs takes place in the tiny air sacs called alveoli in the lungs. The process of inhalation must inflate the alveoli, but it can only do so because of the presence of a surfactant fluid that coats the alveoli and lowers the surface tension of their walls.