What protein found in red blood cells is responsible for carrying oxygen?

The protein found in red blood cells that is primarily responsible for carrying oxygen is hemoglobin. Hemoglobin is a globular protein composed of four polypeptide chains, each of which contains an iron-containing heme group. This heme group binds to oxygen molecules, allowing hemoglobin to transport oxygen from the lungs to tissues throughout the body.

When oxygen is inhaled, it diffuses into the blood and binds to hemoglobin, which facilitates efficient oxygen delivery essential for cellular respiration. Furthermore, hemoglobin also plays a role in transporting a portion of carbon dioxide, a metabolic waste product, back to the lungs for exhalation.

In contrast, myoglobin, while also an oxygen-binding protein, is primarily found in muscle tissues and serves to store oxygen rather than transport it in the bloodstream. Albumin and fibrinogen have different functions; albumin is primarily involved in maintaining osmotic pressure in the blood, and fibrinogen is a key protein in the coagulation process, important for blood clotting.