Terms: 2+, 3+, 4, alpha, beta, carbon dioxide, carbon monoxide, carboxyhemoglobi

Question

Terms: 2+, 3+, 4, alpha, beta, carbon dioxide, carbon monoxide, carboxyhemoglobin, CO2, cooperative, Fe, globin, heme, hemoglobin, iron, methemoglobin, oxidized, oxygen, peptide, reduced

The molecule that exists abundantly in human red blood cells and functions primarily in the transport of __________ from the lungs to the body tissues and the waste gas, ___________ (chemically abbreviated _________) from metabolically active tissues to the lungs is called ______________.

Each molecule of hemoglobin consists of four ___________ chains. Alphabetically listed, two of these chains are called ________ chains and the other two chains are called __________ chains. Collectively, these peptide chains constitute the __________ part of the molecule.

Each globin chain is associated with a protoporphyrin ring structure called a _________ group. An atom of ___________ (chemically abbreviated _________) is located within the center of each of these protoporphyrin ring structures. Iron atoms can exist in an oxidized or a reduced form. Iron atoms with a valence charge of ________ are in the reduced form, while those with a valence charge of ________ are in the oxidized form.

Hemoglobin molecules can only bind molecular oxygen when the iron atoms of their heme groups are in the ___________ form. When one heme iron binds a molecule of oxygen, it makes it easier for a second heme group in the same hemoglobin molecule to bind another molecule of oxygen, and that makes it easier for a third molecule of oxygen to bind a third heme group, and finally for the last heme group to bind oxygen. Thus oxygen atoms bind hemoglobin in _____________ fashion and when a hemoglobin molecule is fully saturated i.e. has a molecule of oxygen 'loaded' onto each heme iron, each single molecule of hemoglobin is transporting _________ molecules of oxygen. The heme iron can also bind to _______________ (chemically abbreviated CO) and hemoglobin transporting carbon monoxide bound to heme iron atoms is called ______________.

When the heme iron atoms exist in the __________ form, the hemoglobin molecule is NOT able to bind and transport oxygen and this form of hemoglobin is referred to as _____________.

Explanation / Answer

The molecule that exists abundantly in human red blood cells and functions primarily in the transport of oxygen from the lungs to the body tissues and the waste gas, carbon dioxide (chemically abbreviated CO2) from metabolically active tissues to the lungs is called hemoglobin.

Each molecule of hemoglobin consists of four peptide chains. Alphabetically listed, two of these chains are called alpha chains and the other two chains are called beta chains. Collectively, these peptide chains constitute the 4 part of the molecule.

Each globin chain is associated with a protoporphyrin ring structure called a heme group. An atom of iron (chemically abbreviated Fe) is located within the center of each of these protoporphyrin ring structures. Iron atoms can exist in an oxidized or a reduced form. Iron atoms with a valence charge of 2+ are in the reduced form, while those with a valence charge of 3+ are in the oxidized form.

Hemoglobin molecules can only bind molecular oxygen when the iron atoms of their heme groups are in the reduced form. When one heme iron binds a molecule of oxygen, it makes it easier for a second heme group in the same hemoglobin molecule to bind another molecule of oxygen, and that makes it easier for a third molecule of oxygen to bind a third heme group, and finally for the last heme group to bind oxygen. Thus oxygen atoms bind hemoglobin in cooperative fashion and when a hemoglobin molecule is fully saturated i.e. has a molecule of oxygen 'loaded' onto each heme iron, each single molecule of hemoglobin is transporting 4 molecules of oxygen. The heme iron can also bind to carbon monoxide (chemically abbreviated CO) and hemoglobin transporting carbon monoxide bound to heme iron atoms is called carboxyhemoglobin.

When the heme iron atoms exist in the oxidized form, the hemoglobin molecule is NOT able to bind and transport oxygen and this form of hemoglobin is referred to as methemoglobin.

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