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.
Air comes in through the respiratory tract into the lungs. Gas  exchange occurs in the alveoli, oxygenating red blood cells. The  blood cells travel through the body, releasâ¦ing oxygen. CO2 is  released by cells and absorbed into the blood stream where it  travels back to the lungs and expelled from the lungs.