Answer:
Myoglobin, a molecule similar to hemoglobin, holds a reserve supply of oxygen in muscle cells (third option).
Explanation:
Myoglobin is a protein found predominantly in skeletal or heart muscle fiber, with a chemical structure that, like hemoglobin, contains a heme prostetic group with iron atoms, capable of fixing oxygen.
For this reason, it is a molecule that allows the muscle to have an oxygen reserve, necessary to meet the demand during movement and physical exercise.
Myoglobin has a red color, depending on its heme group. Each iron element of the heme is found in the middle of the protoporphyrin ring, and its ferrous oxidation state Fe²⁺ or ferric Fe⁺³ is the characteristic that allows it to fix or yield oxygen.
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