Final answer:
An average red blood cell contains about 250 million hemoglobin molecules, which are essential for oxygen transport. Hemoglobin gives blood its red color and each molecule can carry four oxygen molecules.
Step-by-step explanation:
The average red blood cell, or erythrocyte, carries about 250 million hemoglobin molecules. Hemoglobin is a protein that is essential for transporting oxygen throughout the body. Each hemoglobin molecule consists of four subunits, each containing one heme group capable of binding one oxygen molecule. Therefore, a single hemoglobin molecule can bind to four oxygen molecules. Given that there are approximately 25 trillion red blood cells in the human body, the total oxygen carrying capacity is immense.
The red color of blood is attributed to hemoglobin, as it contains iron, which binds oxygen. The lack of organelles in mammalian erythrocytes provides more room for hemoglobin and the absence of mitochondria prevents the use of oxygen for the cells' own metabolic respiration. This specialization enhances the efficiency of oxygen transport to tissues that need it.