Final answer:
Cytochromes are the carrier molecules that have a heme prosthetic group. They play a crucial role in electron transport within the mitochondrial inner membrane, particularly between complex III and IV.
Step-by-step explanation:
The carrier molecule that has a heme prosthetic group is cytochromes. The core component of heme is iron, which allows it to alternate between reduced (Fe2+) and oxidized (Fe3+) states as it carries electrons. Cytochrome c, for example, is a well-known electron carrier protein with a heme group that moves between complex III (cytochrome oxidoreductase) and complex IV in the electron transport chain located within the inner mitochondrial membrane.
This heme is coordinated to the nitrogen atom of an imidazole group from histidine and a sulfur atom from methionine, thus facilitating electron transport. Complex III and IV both contain cytochrome proteins with heme groups; however, these proteins have slightly different characteristics due to the way they interact with other proteins in their complexes.