The fire emoji next to a friend's name means that you and that special, special person in your life have snapped one another within 24 hours for at least two days in a row. You know, like your friendship is on fire? Or...
In adult humans, the most common hemoglobin type is a tetramer (which contains 4 subunit proteins) called hemoglobin A, consisting of two Î± and two Î² subunits non-covalently bound, each made of 141 and 146 amino acid residues, respectively. This is denoted as Î± 2 Î² 2.
Each hemoglobin molecule contains four heme groups. Hemoglobin consists of two alpha chains and two beta chains. Heme groups contain the mineral iron. Most of the hemoglobin in red blood cells is in the form of carbaminohemoglobin.