The mature red cells consists
primarily of hemoglobin (about 95% of the dry weight). The membrane is composed
of lipids and proteins in addition, there are numerous enzymes present in the
red cell which are necessary for oxygen transport and cell viability. The red
cell derives its energy from the breakdown of glucose. About 90% of the
glycolysis in the red cell follows the Embden-Meyerhof pathway. In this way,
adenosine triphosphate (ATP) is generated and used to control the follow of
sodium and potassium into and out of the red cell, maintain the biconcave shape
of the cell, and protect the membrane lipids. The remaining 10% of the glucose
molecules will follow the hexose-monophosphate shunt, where reduced glutathione
is made available to prevent oxidative denaturation of hemoglobin. The
methemoglobin reductase pathway maintain the iron, present in the hemoglobin
molecule, in a functional state (Fe++). Deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA), present in the early stages of the maturing red cell,
are absent in the mature red blood cell.