Final answer:
The primary energy source for erythrocytes is glycolysis, an anaerobic pathway that produces ATP without consuming oxygen, ensuring efficient oxygen transport to body tissues.
Step-by-step explanation:
The source of energy in erythrocytes, or red blood cells, is a process known as glycolysis. Erythrocytes rely exclusively on glycolysis for their energy needs because these cells lack mitochondria and therefore do not utilize oxygen for metabolic respiration. Glycolysis is an anaerobic pathway that allows for the production of ATP without the use of oxygen, ensuring that erythrocytes can deliver oxygen efficiently to the tissues without consuming it themselves. In conditions such as pyruvate kinase deficiency, the final step of glycolysis is disrupted, leading to cellular distortion, rigidity, and ultimately lysis due to an inability to meet the ATP demands of the erythrocyte.