Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A heme group is a complex molecule consisting of an iron ion contained within an organic ring called porphyrin. It plays a crucial role in binding and transporting oxygen in the bloodstream.
5 Must Know Facts For Your Next Test
The heme group is a component of hemoglobin, which carries oxygen from the lungs to tissues throughout the body.
The iron ion in the heme group can bind to one molecule of oxygen (O2), facilitating gas exchange.
Heme groups are also found in myoglobin, which stores oxygen in muscle cells.
Carbon monoxide (CO) can bind to the iron ion in the heme group more effectively than oxygen, leading to toxic effects.
Each hemoglobin molecule contains four heme groups, allowing it to carry up to four oxygen molecules.
A protein in red blood cells that contains four heme groups and transports oxygen from the lungs to other parts of the body.
Myoglobin: A protein found in muscle tissue that contains a single heme group and stores oxygen for use during muscle contraction.
Porphyrin Ring: An organic structure that forms part of the heme group, holding the iron ion necessary for binding gases like oxygen and carbon monoxide.