What is one function of carbon dioxide in red blood cells?

One function of carbon dioxide in red blood cells is that it is bound to proteins or dissolved in solution. When carbon dioxide enters the bloodstream from the tissues, a significant portion of it is absorbed by red blood cells. Inside these cells, it can bind to hemoglobin, the molecule responsible for oxygen transport. This binding forms carbaminohemoglobin, which allows for the transport of carbon dioxide back to the lungs for exhalation.

Additionally, carbon dioxide can also be dissolved directly in plasma or converted to bicarbonate ions through a reaction catalyzed by the enzyme carbonic anhydrase, but the fundamental essence of the correct answer highlights the versatility in how carbon dioxide serves as both a transport molecule and a physiological signal within the red blood cells. This interaction plays a crucial role in the regulation of blood pH and the release of oxygen from hemoglobin (Bohr effect), aiding the body's ability to respond to varying levels of metabolic activity.