Q:

Why do red blood cells have no nucleus?

A:

Red blood cells have no nucleus, because most of their bulk is made up of hemoglobin, a compound that carries gases, such as oxygen and carbon dioxide. In fact, about a third of a red blood cell is dedicated to hemoglobin alone, so no room remains for a nucleus or many of the structures that other cells have.

Red blood cells look like flat disks that travel around the body in blood vessels. They carry oxygen to tissues and remove carbon dioxide from them. Hemoglobin plays an important role in red blood cells, because it carries the oxygen that nourishes cells and takes away carbon dioxide to prevent it from accumulating in cells.

In the mature form, red blood cells, or erythrocytes, do not have nuclei; however, they have not always been without nuclei. In their immature forms, red blood cells did have nuclei. An intermediate form of red blood cells, called a normoblast, expels its nuclei as the amount of hemoglobin accumulates in the developing blood cell. The immature red blood cell can still manufacture hemoglobin without the aid of a nucleus.

Because red blood cells do not have nuclei, they tend to live only about 120 days, which is a much shorter lifespan than that of other types of cells. Nuclei are important to cells, because they control what substances are made in the cell. Without the nuclei to replenish what is depleted in the cell, the erythrocyte will eventually die when it runs out of resources.

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Related Questions

  • Q:

    Do red blood cells have nuclei?

    A:

    Mature red blood cells do not contain nuclei. However, red blood cells that are not fully formed and not fully matured do contain nuclei for a brief period of time during their development.

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  • Q:

    How are red blood cells specialized?

    A:

    According to Springfield Technical Community College, the primary role red blood cells play in the body is to transport oxygen from the lungs to the various body tissues. To carry out this task, the cells are filled with a substance called hemoglobin. Hemoglobin is so important to red blood cells that its molecules comprise one-third of the cell’s volume.

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  • Q:

    Why are red blood cells biconcave?

    A:

    According to Santa Barbara City College, red blood cells' biconcave shape gives them a vastly greater surface area than a spherical cell of similar volume, which allows them to absorb oxygen more efficiently. Red blood cells achieve this shape by losing their nucleus and many other organelles during development. Red blood cells can neither reproduce nor replenish cellular machinery, and they die off in large numbers over time.

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  • Q:

    How long do red blood cells live?

    A:

    A normal red blood cell lives for about 120 days. It takes about two days for the body to manufacture each red blood cell, and about two million are turned out every second. Production of new red blood cells occurs in the bone marrow.

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