How many heme groups are in each molecule of hemoglobin? What ion is at the center of the heme group? How many oxygen molecules can each hemoglobin carry?

Each molecule of hemoglobin contains four heme groups. Each heme group is a complex structure made up of a porphyrin ring and an iron ion (Fe²⁺) at its center. This iron ion is crucial as it is responsible for binding oxygen.

Specifically, each heme group can bind one molecule of oxygen (O₂). Since there are four heme groups in one molecule of hemoglobin, this means that a single hemoglobin molecule can carry up to four oxygen molecules at a time. This efficient design allows hemoglobin to transport oxygen throughout the body, delivering it to tissues that need it for various metabolic processes.