Final answer:
Heme is formed by the combination of iron and protoporphyrin and is an essential component for oxygen transport in blood proteins like hemoglobin and myoglobin. The correct composition of heme is iron and protoporphyrin.
Step-by-step explanation:
Heme is a vital component of various proteins, which includes hemoglobin and myoglobin, and is essential for transporting oxygen in the blood. It consists of iron and a complex organic compound called protoporphyrin. To address the question regarding the composition of heme, the correct answer from the given options is 1) Iron and protoporphyrin. This aligns with the information stating that heme is, in fact, an iron-protoporphyrin structure.
Hemoglobin is a complex protein within red blood cells comprised of four subunits, each harboring a heme group. The role of the embedded heme is to bind oxygen for transport.
Myoglobin, similarly, contains a heme group within its structure and is involved in oxygen storage in muscle tissues. Despite their close association, neither hemoglobin nor myoglobin are components of heme; instead, they are proteins that contain heme as a prosthetic group.